I'm so sick of my boyfriends' crap. what do i do?!?!?

I've been dating my boyfriend for almost 2 years now. Our first year, we were barely dating for 2 months, he had just thrown me a huge birthday party. But a couple of days later I found out he was talking to other females online. He says he never met any of them but I don't believe him. I forgave him, then it happened again. Then again. Now I fear he's still doing it. His family hates me so I had to move out from their house and move back in with my parents. he moved in with me. He's never really here, so in my mind I think he's cheating. This has depressed me to the extreme and before I met him I was already depressed. He never listens to me, always laughs at me and it hurts, and he never understands anything about me. When I need my space I tell him but he's like a bubble gum that's stuck on you. Its only when I'm really pissed off or crying that I want to be left alone but he never understands that, no matter how many times I've told him. He always has to have things his way and that pisses me off. I can't stand him as much anymore, I'm constantly angry at him. I'm so lost I don't know what to do. If I stay I want to be happy with him because I do love him and sometimes he does manage to make me happy. But if I leave him, my depression will sky rocket and ill feel like I have nothing else to live for. Please help me. No rude comments. This isn't a joke or a game. This is my life and I have no one else to talk to. My parents have never even been there for me either. I feel alone in this world.