The more I here the more I just shake my head and have to say I agree with the other ladies.
This guy honestly doesn't sound like he's poly. He sounds like he's an emotional predator who uses manipulation to get women to give him sexual and emotional power over them.
If I were you I would RUN, not walk, but RUN away from him.
You are worth SO much more than being treated like second best just because you are kind, loving, respectful, and open. He's taking advantage of a beautiful person. DO NOT let him do that to you.
((hugs)) and trust me, you will find someone (or ones) much better. You do deserve that.