Ack! I had a lovely reply with quotes and deep, thoughtful answers- then I waited too long to post and lost the whole thing. Wah! I forgot about that with these forums.
First- thank you. All of your responses gave me great things to chew on, think about.
We are a MFM 'friendship,' that I have thought was more than a friendship for a long time (like at least 5 years now). I have been married for 18 yrs. The other M is my husbands best friend, I'd also consider him my best friend also. The three of us are very 'there for each other,' no matter what. We already have a relationship that makes others in our small town arch their eyebrows. Plus, we happen to be casual nudists. That has nothing to do with sex, but speaks to our closeness.
I guess the elephant in the room is that over time BFF and I have developed feelings for each other- we have a lot of emotional intimacy and desire physical intimacy. I tried to talk about this a few years ago and everyone freaked out and for a long two years we were pretty distant.
Confusing things is the fact that I am very open, very liberal sexually and it turns out my husband is/has.... childhood issues? emotional security issues? a dependence on sex with me that is very co-dependent? Gosh, I don't even know exactly what at this point. I think perhaps he'd just repressed having feelings about sex and sexuality for most of his life, maybe. But he loves me- he has been very patient while he tries to understand how I think about life. I think perhaps he spent too much time in the Catholic church, but I try not to judge.
We took Kevin's advice and talked as a group, the three of us, very plainly in a healthy way. No jabs, no anger, etc. It was amazing! That opened up things for husband to say what he is comfortable with right now, then BFF and I to be able to communicate/hang out without feeling like we were doing something wrong.
Husband and I also have an appointment for counseling. I found someone in our small town who listed experience with open relationships/polyamory/etc in our small town, yea!! The three of us have no interest in listening to someone tell us that we shouldn't be friends. That said, we all need help navigating this, I think.
But it turns out breaking the ice and having that first conversation is the hardest. Also, moving forward requires letting go of the past and being willing to be uncomfortable. It's a big roller coaster, self discovery. Some days (today), I feel pretty positive, others I feel sad that we are maybe risking everything or 'doing this wrong,' etc. And my husband is struggling. I take it all very personally, but a lot of this has to do with his own life journey, I think. He is realizing that too. Dealing with this is just forcing him to unpack some carefully stowed baggage.