My Relationship

ok. so this is my first post and whatnot. but i have something i just really have to write out. unfortunately its not happy happy joy.
so ive been dating my current boyfriend for almost a year now. there has been some major issues though. some really unhappy moments. and some really bad problems. see im seventeen years old. im a boy virgin and im bi. so this poses a problem. my boyfriend will be nineteen in two weeks. ive had numerous boyfriends and girlfriends. i used to fool around and whatnot but i realized that i shouldnt be doing some of the things oi was so i stopped and since then sexual stuff has really made me uncomfortable. but its not like its like that with everyone. i feel bad because im just not sexually attracted to him.. but i am sexually attracted or have been attracted to other people and its just not much fun. so my best friend called me today saying that he needed to talk to me about my boyfriend. it turns out he sent a text message to one of my other friends saying that if he werent with me and she werent with her boyfriend he'd be trying to get with her. and that was like a slap in the face to me because we broke up once before because he had cheated on me with my ex girlfriend. and had sex with her behind my back and that hurt too. but i thought we had worked our honesty issues and trust issues out. apparently i was wrong and it just sucked really bad. so now im thinking that i may have made a mistake in letting him back in. i dont think he respects me. and it hurts knowing that he doesnt respect me. i mean if he did.. shouldnt he not be bothering me about this stuff and pushing me so hard for it. i dont feel like hes respecting me. and i just dont know what to do. it really sucks.. HELP