AGH! WHY DO ALL GUYS HAVE TO BE FUCKIN LIERS AND CHEATER???!!!!!!

my now ex-boyfriend, whom i though was the right guy for me, cheated on me! This always happens to me and im fuckin sick of it! first-the psycho second-the liar and now-the cheater/lier
The day we got out for fall break the first thing he did was makeout with another chick. my friend told me that they did a bunch of sexual things but not sex. when i found out i tried to talk to him about and of course he lies to me about it. and the next morning one of my best friends told me he was walking with her holding hands with her in the hallway..
and then i fell to my knees crying at school in the hallway for a few minutes. and then i went and found him and asked him about it and he said 'i would never do that to you, i love you, i would never hurt you' and blah blah blah! so i went to first hour and roughed it out, then i got to second hour i started crying when i was telling my friend. then i bumped into my best friend's girlfriend and she said he's been telling her he loved her..
then i saw my other friend and started crying on his shoulder, then i went outside and there he was standing.. i walked up to him and just stood there, then of course the idiot he is asked me what was wrong, and his friend yelled in his face 'what do you think is wrong with her!' and then he looked down. then he hugged me and i ran to my 3rd hour, and when i walked in the class room and saw i was so upset i cried and couldn't calm down and stop, so my 3rd hour teacher had to send me to the counslers office to talk about it. and walked me down there and then i had to talk the counsler about it. i felt better but i was still upset. after third hour me and walked to my locker and he was there waiting, but i knew what i had to do. so me and him started walking and then i told him, that we should break up bc of what he did. and all he said was ohkay and im sorry then hugged me and went to class.. and that was the last i heard from him for the rest of the day...

Then when i got home, i went to rehearsals for the anime club. then when i got home i checked my myspace and he sent me a message saying he was sorry and the said the things he should have said to my face that day. and then he finally admited and then i haven't talked to him since then..

its really upsetting and idk if i can trust another guy anymore.. this kind of thing has happened to me 3 times. and i don't know what i do wrong to make them cheat or lie.. twice the guy picked the girl who would have sex over the girl who isn't willing til marriage and doesn't do drugs. and i've been lied to so much i can't stand it anymore....