Am i stupid for being jealous of her?

[Purple]

I'm not really sure where to start and no matter what i write i'm still going to sound like a bad person but trust me i'm not. Very long story short, me and this guy from school got back in touch via Facebook. We met up and after meeting up a few times we ended up sleeping together. That was the biggest mistake of my life because not only was it my first time but afterwards he treated me differently and only talked about sex when we spoke. I felt like crap but yet i really liked him. This "thing" (whatever it was) carried on for about 6 months or so.

Then he got back with some ex girlfriend who he knew from uni and who lived near him (he lives miles away from me). Well, at first he said he just wanted to be friends because he was no longer single but then when we met up he tried to kiss me and touched me inappropriately. At the time i was so blinded by my feelings that i thought that meant he liked me (stupid) so i let him do it. The next time we ended up sleeping together behind his girlfriend's back and carried on up until about 2 months ago. He text me one night asking to meet up for a drink (i didn't reply) the next day i find out that he's moving in with her. I decided i couldn't do it anymore so i text him telling him to leave me alone. He asked if we could meet up and be friend but i said no. The next day he removed me from Facebook and haven't spoken since the middle of March. The first few weeks i was very upset but now that it's been over a month i feel slightly better but it's still hard sometimes. I hardly go on Facebook now because i don't want to see anything that will upset me etc I'm more disappointed with myself more than anything because i was told what he was like and i never thought i'd be so stupid. I still feel angry that he's gotten away with it.

Sometimes I feel like it happened because I wasn't good enough. I mean, I've seen pictures of her and she's not a supermodel or anything, she's just a normal looking girl like me but she's blonde and her family is well off (unlike me).