What to do with this new guy?

Okay, so im with this new guy, I’ve been with him for bout 2/3 months now, and we had sex pretty early in the relationship, (ino stuppid thing to do ) so right, he was so up his own bum for the beginin of the relationship, well actully up untill last week, but it made me feel like crap, hed always make comments that he was better than me, and anyway, he was always really over protective over his phone, which I can understand, but he blamed it on his parents checking it, which they dont, anyway, ironikly the week before last I was thinking of breakin up with him, I suspecting him of cheatin or sneakin around behind my back ( I always new he was a flirt) I cudnt take the constant weirdness he had around me, so I was getting up the courage to do it when last monday, I got a email of one of my friends saying that he’d been tryna get with another girl, so I got upset, and when I spoke to him, it took a lot for him to admit it, he said he was joking, and he told me it was two months ago, when wed first got together, anyway, so I stayed with him, stupid thing as on the tuesday night I found out he’d asked her to do stuff with him (the same girl he asked out) which he admited, and I forgave him for, and then, I found out on the wednesday, it was the week before hed done it, when he told me it was 2 months ago, and I was there and ready to break up with him for, but he was like oh I love you, I was joking and crap, So once again I did a stupid thing and stayed with him, and he told me he was gnna change, and he did, the end of last week, he was nice to me, he started treatin me right, not like crap, but I can see hes going back to up his own bum, and I just dont know what to do… Sorry, I know this is confusing, I jsut dont know what to do, All my mates are sayin break up with him But I want too, but at the same time I dont Any advice will help :) Thankss x