Is it normal that i want my boyfriend to cheat on me

My boyfriend and i have been together for two years,and have been living together for a year(with his folks). We recently moved into our own place and have been nesting. It has been fun and extremely exciting, but our sex life has completely fizzled. I truely thought that the normal thing to do is move in and have sex on every surface. I think its both of us,but possibly myself more so. I dont feel desirable and i think that may be the reason behind it. My boyfriend has a habit of joking about my appearance. He has pointed out every flaw in my body and constantly tells me about them,sometimes when we fight he says that he isn't even attracted to me anymore. I'm not interested in putting make up on,or dressing up as i dont feel beautiful or sexy EVER. Im not a bad looking person,i have been known to turn heads and have men(in the past)go silly over my naked body. But it doesnt matter if it doesnt come from my current boyfriend. When we do have sex i have to close my eyes and pretend he's someone else to enjoy it,i think thats because of all the anger that has built up inside towards him. I almost want him to go out and sleep with someone else,so he can see that im not as bad as he thinks i am. I love him very much,and other than this problem he is a terrific boyfriend but i just cant seem to get passed this.