I am so sorry things happened like this. You have my sympathy. This is just about one of the worst ways he could have approached it, just going off to talk some lady up after taking things said during sex fantasy/play as actual consent. And he wants to move her in with you? What's
wrong with him?

He thought you'd just be like "Yay! Yippee!" or something?
I think setting up couple's counseling is a good move.
I think you might ask in counseling if he's trying to wave the "polyamory" brush to "whitewash" a cheating affair that had already been underway, as a means to continue both relationships out in the open now and assuage his guilt about the cheating start. Sometimes people do that.
He canceled the meeting, but the woman is willing to wait to see if things change. He talked to a couple and their girlfriend and they told him he fucked up. But then he told me he wanted a relationship that the three of them have. How, when I didn't even know this person existed?
I think the friends are right. Your husband behaved poorly.
He didn't get far, but he stepped out and cheated on current agreements. Dinged trust. So Lady is waiting in the wings? A lot of people who consider healing from a cheating make dropping the cheating affair partner a prerequisite. Like, "Nope. If you still are going to be with the cheating affair partner, I don't want to work anything out. I prefer to separate or go right to breaking up."
Nothing personal against Lady. He may have lied/told her stories. But no, you actually don't have to be here.
Him wanting a relationship like the poly friends have? That's nice. He can want things. Still doesn't mean he's gonna get one. Your consent to do things or not belongs to you. And the theoretical Lady? Her consent to do things or not belongs to her. For a 3-person thing to happen, all 3 people need to vote "yes," and he doesn't have that here. You do not agree.
And even when all 3 people agree to try a 3 person thing, be it a V, or whatever model, sometimes the compatibility just isn't there and you end up breaking up, just like in any other dating. Shrug.
I feel like I'm not enough, like I'm not attractive anymore, like I'm not respected like I should be. I came to you guys because I wanted to know your opinion. Does it ever work out when one is monogamous and one is poly? I don't want to leave him, but if this is that important, I will.
Be careful you don't diminish yourself and beat yourself up as a result of HIM thinking or doing stupid things. Respect yourself more than that. His poor behaviors are not a reflection of your worth and value.
Are you enough you? Sure. I imagine you are a nice person. But are you enough for HIM now? Maybe not, if he's changed over time and doesn't want monogamy any more. If he wants polyamory or other non-monogamy, and you prefer strict monogamy, then this relationship is no longer compatible. There's no getting around that. Because you are one of the people involved in the relationship, there are going to be strong feelings. But in general, if people are not compatible anymore, they don't have to be together anymore. It is what it is.
Are you still attractive? If you are keeping yourself neat, clean, and presentable, why not? You might not be attractive to everyone in the world, but you'd be attractive enough to some. People can't help having preferences. Some people really dig redheads, some get freaked out by gingers. It is what it is. It's the same with other features besides hair color. Some like tall, some like short. Some like slim, some like plump.
But that doesn't mean HE is still attracted to you.
You yourself may be losing attraction to him due to his poor behaviors lately. If he's not respectful of you, that's gonna be a HUGE turn off. And you will be looking at him different now. You deserve to be treated well and respectfully in a relationship.
You might have to reassess him. He may no longer make the cut for what you seek in a partner. Sometimes people can heal from cheating and choose to continue together. Sometimes it's a dealbreaker and they heal on their own and stay apart.
Update: We have an appointment with a relationship therapist in a few weeks and we have talked a little more but he seems nervous about bringing up what he wants and hurting my feelings.
Honestly, he's ALREADY been hurting you and your feelings. So, tough. He can feel nervous or whatever in therapy. But YOU? You can talk plainly and sort what needs sorting, with the counselor's guidance. Just put it right out there. That's why you are in counseling, right?
Pussyfooting around isn't gonna help anything, and honestly, therapy gets
expensive. And you have your own bandwidth for time, energy, and emotions to manage. If he's going to waste money and your bandwidth, why bother with couple's counseling? You could use the money and time/energy for your own individual counseling instead, which might be better use of those resources.
It's time to put cards on the table PLAIN.
I'm not saying that to be mean or anything. It's just that you sound like you've been under a LOT of stress and like you might prefer restabilizing your own emotions/life and getting through this, rather than dragging it out, or doing extra emotional labor for him right now, like worrying about his nervousness. He can worry about his nervousness on his own.
It's fair if you each deal with your OWN feelings right now. Put your own oxygen mask on first.
Things are better between us, but I am so anxious.
Understandable. He stepped out/cheated on agreements, rather than actually renegotiating agreements properly with you. He doesn't seem to understand actual consent.
So viewing him as a potential hinge with two partners-- how does he look to you? If this were me right now, I'd be voting: "No confidence. I'll pass. I'm not willing to poly date with you. You seem like a mess."
Just because he wants poly now, doesn't mean you have to go there with him and be part of his new poly network. It doesn't sound like this was part of the marriage vows. You can't force him to stick with the old deal if he doesn't want it anymore. But you don't have to sign up for some new deal either.
You might want ZERO polyamory. Or... you might want polyamory with BETTER BEHAVING partners than him. Shocker!
Just because you were compatible for monogamous marriage doesn't mean you automatically will be compatible for polyamory.
I have so many questions, but don't know if I want the answers.
For your own sake, I suggest you ask all the questions you need to ask in counseling and deal with the answers. Your long-term health and well-being is your responsibility. So get all the data you need to know and make the choices you need to make. You were blindsided by his poor choices. That doesn't mean you have to sort the fall out with blinders on.
He says he loves me, but I feel like I'm being put in this box labeled "fragile wife who can't do what I want."
You might not want what he wants, but you aren't "fragile." You are rightly upset and anxious because he cheated on agreements, dinged your trust. You were just living life. Now you have to deal in all this stuff due to his unwanted behaviors.
If he can't manage to keep his agreements in monogamy, how would he keep his new poly agreements? Poly isn't magic. The relationship shape isn't what makes people keep their word/promises. There are people who cheat on their poly agreements too.
You sound like you're in the shock stage right now. Kinda wondering when you are going to hit the anger stage. It's probably good that you have counseling lined up soon. Expect your emotions to go all over the place as you sort this out.
I worry that every time he touches me or we are intimate it's because he has to, and that I'm just some "good for now" person.
You don't have to share sex with him right now if you don't feel like it. If it's not a "joyful yes" thing for you, don't share sex now.
But please do not denigrate yourself just because he did stupid things. You have enough problems right now without piling on "I am my own self bully" on top of it.
I don't feel like I'm truly wanted by him or that I don't satisfy him. And that there's a part of him he won't share with me but will share with some stranger. I feel like I have to compete with some shadow person. I'm willing to discuss and negotiate some of the BDSM stuff but for him to have a whole other relationship that includes sex is not for me, at least right now. I'm terrified that he'll leave me or I'll have to leave him if he refuses to compromise.
I encourage you to think about individual counseling for yourself to unpack all that, especially the last part in bold, because that fear might harm you, tempting you to stay in things that are no longer compatible, or things that hurt you, just because you are scared to be out on your own.
You have to be able to say "I love you a lot. But NO, not even for you will I do stuff I don't really want or stuff that hurts me. That's asking too much."
So... take a time out. Don't share sex if you aren't into it right now, and get to the counseling appointment. Consider individual counseling too, if you need more support. You could ask for a referral from your couple's counselor.
Put your own oxygen mask on and have firm boundaries with your spouse. That is my suggestion to you.
You might read:
Feeling unhappy in or unsure about your relationship? Having problems you don’t know how to work through, or don’t even know if you should? We’ll talk you through making these choices, including how-to’s on conflict resolution and doing breakups better.
www.scarleteen.com
if those help you assess.
What is your desired outcome?
Galagirl