I'm sorry this has been hard for you. It is tough and will push you farther in relationships than you think possible. I can almost guarantee that.
I wonder if perhaps its time to think about what you want in your love relationships. He will always be the sort that talks about other women and ex's and need more than one it sounds like. Especially if he is bioplar. Being sexually open is part of the diagnosis I believe. Nothing wrong with all of that, but if you struggle with it to the point of it influencing your good mental health then I think its time to do some serious soul searching as to whether or not this is a positive relationship for you.
If you haven't already done so, and I am going to assume you haven't, just by how you come across so far, I would suggest reading a lot on here. It will help you get a feel for how people live and find a positive lifestyle through polyamory. I suggest that you read together so that you can be on the same page and then slowly put a foot in before jumping ahead to imagining all out sex parties with your man being the centre of attention. Not that that is how we all live :O but as an example.
It just doesn't work to go from 0 to 100 in my opinion. Its just not sustainable and falls on its rickety foundation. At least that is what I have noticed anyway.
Anyone want to be friends on Facebook?
Send me your name via PM