Boyfriend Troubles

Boyfriend troubles, who doesn't have them? I love him, honestly I do, but since I have been in bad relationships before I worry. Then he has this best friend that is a girl and he spends more time with her than me. I know the girl has a boyfriend, but I honestly think she has a thing for my boyfriend which is her supposed 'friend'. I mean with one of my ex's he was my best friend and we held a sexual relationship, so forgive me for thinking that maybe my boyfriend and his best friend might be doing the same thing. Also I have gone through his phone and mp3 player, I see these pictures of all these girls and I ask him who they are to him and he says they are just friends and one is a suppose long distance sister. I had a supposed long distance brother until he proposed to me, so I question the relationship between his long distance sister. I have had bad relationships and they were really messed up. So I constantly worry what's going with my boyfriend. I just worry about him too much and I get pulled away from my college classes. I want to be with him, but I feel like I never really can. Aslo that 'best friend' of his threw my sweater atop of my face one time when I was kind enough to lend it to her because she was cold, well now I know not to even bother with it. Confused and utterly need some help and supporting advice,
Temptress Anger