Needing advice!

Megan

So I've been with this guy for almost 2 years when we first got together he cheated on me (he was asking his friends that's was girls to send him pictures) he says it's not really cheating cause it's like porn... anyway I couldn't handle it anymore because I fought him begging his ex (who he said he hated) to meet up I tried to leave him he said no I'm sorry please let me show you I can fix this... he deleted some girls off his snap chat... it got better for a while but I can't trust him at all... I've tried my hardest but I can't trust him to go to the store alone.. I'm not happy anymore he has changed he is trying his hardest to show me he won't cheat again but we fight ALL the time! I started talking to a friend of mine that I've had feelings for but I pushed him away cause he was going into the Air Force... I told the guy I was with that I didn't want to be with him anymore and that I want to be with my friend in the Air Force.. I feel terrible but he makes me happy just to hear his voice makes my day so much better.. the other guy is still living with me and he acts like everything is just fine when clearly it's not and now he's telling people im a lying cheater that was sneaking around... it kills me because I never meant to hurt him but I'm not happy! Am I really a terrible person? Please be honest..