I've been married for nearly 11 years. It was mono to start. It was frustrating and heartbreaking, and I felt stifled and broken. (I often used an "eagle in a cage" metaphor.) My life only improved when I did the following:
I quit pretending to be something I wasn't. I compassionately explained that I had failed in this marriage, because I simply hadn't done the true "dirt work" beforehand. I wasn't cut out to meet the commitments I had promised to keep.
I explained, "Yes, I do love you, I always will love you, but I can't be the kind of wife I promised to be." I gave him the promise that if that meant divorce, I would respect that and honor him by not dragging him through court BS with our four kids. I would settle with him and ensure that I never put in place something that would make his relationships difficult (like moving away, causing battles over custody).
I then committed to having no lovers who were not fully accepting of who I truly was.
Then I went about discovering who I truly was. "Being poly" is only one aspect of a person. I identified my true world view, values, morals, etc. Mine, not the ones I thought were mine because that's what I had lived my whole life. (This required a great deal of reading.)
Then I started looking around my life to see who/what was in it that was counter to my true world view, values, morals, etc. I started gently weeding these out.
Additionally, I began looking at myself to see what actions I was taking that went counter to my true world view, values, morals, etc. I made a list and, one by one, I have been "discontinuing" those actions. (Hard work, that one!)
I also began looking for what things I wasn't doing, that I should be doing, and began doing them, such as: working out; eating healthy; being considerate, for real, all of the time; controlling my emotions instead of letting them control me; controlling my behavior, not saying/doing anything that went counter to my goals.
It sounds like you really need to stop yourself and take a long hard look at what it is you truly want for your life. Not for the bedroom, for your life.
Do you want casual sex partners, a great job, a small studio apartment, a tank full of expensive fish?
Do you want to have a poly-fi relationship with two women, or three women and two men, or six men and four women, or...? I (just made all that up.

)
Do you want to be free to have a couple deep meaningful sexual relationships, and some deep meaningful non-sexual relationships, and some casual sex partners?
Do you want to live in the city, suburbs, country, another country?
Do you believe in a "bigger picture," like the "Gaia Theory," or "deeper enlightenment" for everyone?
Do you have children you need/want to stay available to, limiting your ability to be where you prefer? If so, how are you planning to negotiate this in the long term?
What do you want to impart to them in regards to relationships, lifestyle, etc.? Would you like them to not make the mistakes you have made, and are making?
Do you want to impart to them the importance of continued learning after formal schooling ends, that loving people unconditionally is more important than having what you "want," that you must always be true to yourself? (I am not pushing for any given thing, just trying to brainstorm thought-provokers for you.)
Since you said you'd started a family, I assume you have at least one child. And you were married 9 years. and have been on your own for a little bit, so it stands to reason that at least one child isn't grown yet-- I wonder if you've considered what you are teaching them with your actions. For starters, divorce is devastating, more for the child than the parents. They need extra support, reassurance and attention from both parents to ensure that they internally feel that they will remain secure, even though the biggest security they had has fallen apart (their family support system).
But more then that, they need to know "what a great man does as an adult" and "what a great woman does as an adult." Obviously, you can't teach them what a great woman does. You've implied already you aren't a woman. But if you insist on allowing women who are not suited to being with someone like you, to "punish" themselves, and you, by being with you, you teach them that there is something wrong with your type of loving (polyamory).
You also teach them that relationships aren't "sacred." I am not lecturing you on being one way or another, per se, but if you and/or she aren't happy with the relationship, but you stay in it, that isn't "sacred." Even a one-night stand, where both people leave with no regrets, is more "sacred" then a lifelong marriage where one or both partners are obviously miserable.
Additionally, you teach them that their needs don't really matter, because you aren't standing up for your own. And you teach them that either their mother isn't worthy of respect, or you weren't worthy of giving it, and/or are a liar, because you left her "due to being poly by nature," but you are with someone else who can't accept that, so obviously there was either some other issue, or you are just fucked up.
It may seem like a young child wouldn't be able to figure these types of things out, but I assure you, they do. I did when my dad left my mother (for good reasons, I might add). My son did at age 4 when his father left me (when I was cheating). I know he did because he was vocal to his father about it. When his dad left, it was obvious to our son (we didn't fight, we remained very amicable) that his dad was mad "or he wouldn't have left the house," as he said. He told his dad, "You tell me and D (his older half brother) and A (his older half sister) that if we have a fight, we need to get over ourselves, 'cause we're family. You and GreenGecko need to get over yourselves, 'cause we're family!"
A very 4-year old view, but the underlying message was, "Dad, you are a liar, and I see it." It broke my husband's heart, to say the least. (At the same time, it caused him to lose his temper, because for the first and only time, he thought I must have been "talking shit" about him to our son. I wasn't.)
The bottom line is, kids do "create" themselves based on what they see their parents doing.
You are disrespecting yourself, and the women, and the "unsuspecting" boyfriend with your actions. Your children will pick up on that and it will color their futures, too.
You deserve better.
The women deserve better.
The other boyfriend deserves better.
You can't do much to make the women or the man go out and seek better. But you can hold yourself to a standard that respects yourself, your needs and your rights.
You can hold yourself to a standard that shows your children the types of relationships you want for them.
If you have a daughter,
you can show her how you expect a man to treat her and how you want her to treat men (see below). You do this by treating her mother (as your ex), and all other women with respect, even if they don't respect themselves enough to insist on what they need. (I.e., don't date women not cut out for poly.) And treat your ex with the loving (not sexual or misleading) kindness you would show your own mother.
If you have a son,
you can show him how you expect him (as a man) to treat women and how you expect women to treat him, by doing the above, AND by insisting on being true to yourself and only being with women who are healthy and whole and capable of complementing your life, not women who bring unnecessary drama, headaches and heartache to your life.