I can't let anyone get close to me how can I get better?

I am really insecure about letting people get close to me to the point where I am mean and immature. I force people to be repulsed by me and I act in ways that no one would ever want to be around me or be my friend, not even my pets or family. I'm cold, distant, manipulative, and sometimes I can be evil. If I were religious I would think there was a demon living inside me. All I think about is suicide, and when I die I know this way it will be a relief to them, not a tragedy. Last night my boyfriend was trying to gross me out and I was so turned off because I understood what he was doing. So we broke up and I can't sleep, eat, or even cry because he was like don't cry, after we broke up. Usually if I cry I feel better, but I can't knowing he's using reverse psychology on me. There's constant manipulation on his part I always feel like he's controlling me psychologically and I couldn't take it anymore. Everything would've been fine, but his ex girlfriend called him to eat dinner with her and her family and I told him thats not cool and in his mind he's thinking who else is going to feed me delicious food. But its his ex... so thats not supposed to make me uncomfortable at all? It gives me anxiety that I have to trust him around her and it makes me really insecure and he's like what the problem. It pisses me off. I can't be with him because of THIS reason and he doesn't get it. I think he might even like watching me be uncomfortable and insecure.