Relationship Paranoia?

Okay so the last guy I was talking to, I fell extremely hard for. He constantly hurt me over and over again. I never once thought he was cheating or doing anything behind my back, but he was, and even after I found out about it I trusted him completely the next time. Now with my current boyfriend, weve been dating for almost 5 months now, im having a really hard time trusting him. I love him to death. He lives right across the street from me and has never been unfaithful. Every little thing he does, I turn it into a crazy scenerio that didnt happen/ wont ever happen. I tell him about my paranoia everyday, and he goes to such great lengths to prove his love to me every single day. When im not with him, I feel like hes doing something behind my back and I think of the worst. When I am with im, I feel like everyone around me is ganging up on me and mouthing things about me behind my back. I cant even find myself to trust him around another girl, even my best friend of 10 years. He really doesnt deserve to be put through this and I dont know what I would do without him. I dont want this to ruin our relationship. Please help):