confused ??

I stupidly cheated on my boyfriend, but everytime he hangs out or talks to other girls I get really jealous and angry. It's almost like I don't trust him, yet he hasn't don't anything wrong like he hasn't cheated on me or anything he's been entirely faithful. I always feel like he's doing something to hurt me and he gets mad at me and he says "you don't trust me"... So, why do I act like this? Is it just major jealousy? I know, it's really confusing