I'm so sorry for your pain.
Your boyfriend sounds like a complete tool. He is giving poly people a bad name.
Please dump him. He doesn't deserve your love.
Being in love with someone is no reason to stay with them when they are treating you badly. Losing a love feels like it will kill you--but it doesn't really kill you.
I was in a similar place when I was in college--in a relationship with a poly guy who treated me horribly. I didn't know anything about poly, but I was intrigued by it and took his word for how it was supposed to work. I thought he was a much better person than me because he didn't feel the horrible jealousy I felt. When I talked to him about things that bothered me, he told me it was my fault.
He was my first sexual relationship, so I felt he was really special.
Eventually he dumped me in a cruel way, and I spent months in a deep depression, consumed by anger that I had never stood up for myself and dumped him when I had the chance.
When I finally got myself together and went on a date with another guy, I realized IMMEDIATELY that MOST PEOPLE will treat me better than the douchebag I lost my virginity to.
If I'd had the courage to get out there and go on EVEN ONE DATE with ANYONE ELSE IN THE WORLD while I was in college, I would have learned enough to not have spent almost two years with a "poly" guy who did not give a crap about me.
Like you, I am shy and awkward and do not always feel attractive. But you know what? I am cool and kind and smart and have interesting hobbies. Lots of people like me.
Losing your first love is hard. But I don't see any way you can get this guy to understand your needs. He's already dismissed them.
Please know that you can do WAY better this guy. I don't even know you, but I know that!
Single, straight, female, solo, non-monogamous.