Why do I cheat on my boyfriend even though I love him?

My boyfriend and I have been together for a little over 9 months. We're both in our late teens, and I've never felt this way before in my life. I love him more than anything in this world, and I know he feels the same way. He was also my first. Despite my strong feelings towards him though, I have cheated on him on more than one occasion. I never feel pretty enough for him, smart enough, etc. I always feel inferior and like he deserves better. I've tried discussing my inferiority complex with him before, and the conversation goes the same way each time. He reassures me that I'm everything he could want, but no matter how much he stresses this, I never believe it. Is it the media? I don't know. His family dotes on him a lot, and CONSTANTLY talks about how perfect he is (especially his mother). My own family is nothing like that - I'm not close with them, and they always focus on my flaws instead of my strengths. My boyfriend's mother is also obsessed with "sexy women". She's always talking about how she used to bartend in a strip club, she talks about other women that are sexy because of X, Y, and Z, and stuff like that. Which is fine, there's nothing wrong with appreciating the aesthetic beauty in another human being, but she turns women into objects the same way that some men do. Whenever I'm around her, I end up feeling ugly and worthless, even though she doesn't target me personally, and even though a lot of times feel like an extremely attractive and cool person. She also stresses how he finds the chicks from Paramore and Evanescence so hot. Which is fine, but it keeps coming up over and over again with her. And they're gothy girls. I'm not gothy at all. So it makes me feel like I'm not quite what he wants. Most of my close friends are guys, and they encouraged me not to feel that way. I model underwear, and they told me that he should feel lucky he's dating someone as sexy as me (yeah right!) But the point is, they were my support system, since my family isn't exactly positive. But my boyfriend's mother hated the fact that I was friends with so many guys. She had it in her head that I was going to cheat on her son, so she ordered me to stop speaking with my friends if I wanted to maintain the relationship. There's so many things going on at once, and so many reasons why I don't feel good enough... people always say men have "fantasies" about other women. I don't find that fair. I don't have fantasies about anyone but my boyfriend. I guess I sort of put him on a pedestal, but I find him the most appealing out of anyone alive. He's all I could ever want, he's perfect, I don't want anyone else. because of this, I start to think to myself, "alright. He's not so special. I'm not perfection in his mind, like Amy Lee and Hayley Williams, he wants something else, fine, then I can do something else, too." So a few times I have cheated on him with guys I barely knew. The opportunities arose, and I took them. It wasn't because I found the guys sexy. It wasn't because I don't love my boyfriend. In fact, it's BECAUSE I love him so much, it hurts. I don't want to feel like I'm not good enough anymore. I want to feel wanted. I want to be someone's world; I want someone to think I'm perfect the way I think my boyfriend is. I fooled around with other guys to try to separate myself from my boyfriend; care less. It's because it hurts so much all the time. Every day I don't feel good enough for him. When he says "I love you", I feel like it's a lie. Or if it's not, like it's a joke, because I'm not in his league. I never felt so bad about myself in my life. I don't know if it's the media, or his mother, or the fact that he likes goth chicks or what. I just know that I feel terrible all the time. I've asked him to be platonic friends before, because I feel like I'm going insane, but he refuses. He says he loves me too much, and he cries whenever I mention the idea, because he doesn't want to have to live without me. I don't want to be without him either, he's my best friend, and the love of my life. I just don't know how to overcome all of these awful emotions. Also, I was raped as a young child by my father. Maybe that's related? I need answers. Please someone help :(