demonicz

Ok I need some help.
This may be long, bare with me!
ok...
...right so last month, if you remember, I broke up with the abusive Ex. Ok so understand we were dating for 4 years, long ass time. I recently have met someone else who couldnt treat me any better. Like he makes me all smiles, some of the reason for the move to Texas, aside from school.
Now my problem is this..
...For the past few weeks the ex has been making me feel bad. Telling me I was wrong in moving from him to someone else, and that I hurt him, and that he missed me blah blah blah. Tonight I found out that the day after we broke up HE was making out with some girl in his hot tub. Fast forward a week or so, he signed up to VampireFreaks.com [ha!] to meet girls [Now know that most of the girls on there are 17 around our area - hes 23]. Fast forward another week, hes already slept with her. Now this is while he's throwing me the lines of "i love you and miss you" bulshit, and still trying to make me feel bad. This girl just turned 17, still in high school.
My problem is this..why do I still care. I mean I dont care about him, but it bugs me sooo much that he did that. I mean I wasnt that much better. But I actually found someone I liked and wanted to be with. He's just fucking random girls.
for some reason I cant just let it go and pretend he doesnt exist. Im torturing myself, and he's drowning me.
I dont know how to get over it, cause I really want to forget him and Im finding it hard to accept the fact that he could go from me to that.
He makes me feel so shitty about myself...and I let him
Im a mess