First off: if you want out contact a women's shelter. NO men are allowed there AT ALL! The locations are generally little known to any who aren't involved with them. Change your cell number and anything else he knows about that can be traced back to you.
A little story: Breathes (my primary) at one time had an oso. The first time they had sex I was not in a good place. Jealousy came to the fore and a whole host of emotions I didn't know how to deal with came along for the ride. He took the time to listen to me, actually hear what I was saying. He didn't accuse me of being manipulative or anything of the sort. He talked me through it, explained things the way he saw it, helped me to sort through my feelings. He helped me find ways to cope. He changed his date times to times when I was occupied with other things so I wouldn't dwell on what they were doing.
Polyamory is NOT a one way street, it is not 'my way or the highway'! It's an awful lot of give and take, talking and listening, compromising. Your relationship is anything but. I wouldn't classify it as a loving, caring relationship that's for sure.
You may be poly, you may not but right now is not the time to find out. Right now is the time to learn how to like and love yourself again, how to not let others who are like him NOT get to you.
I've got to get ready for my 16 y/o sons birthday party but I will be back on in a few hours.,
There are as many ways to do polyamory as there are people practicing it!