boyfriend of 4 years told me he is not sexually attracted to me anymore

This morning when I went to pick my boyfriend up from work at 6 am he told me that he wasn't sexually attracted to me anymore. He told me he loves me so much but that the sexual aspect hasn't been there for a long time. he claimed he has nightmares about me leaving him so he doesn't want me to think he is leaving. he told me it didn't have anything to do with the way I look, but that a dry patch we went through with sex ruined it for him. We went through a dry patch because early on in our relationship he cheated on me with his ex fuck buddy and I found out. It really hurt me for a long time and it was hard to be sexual with him. In the last year or so I've really tried to get better about it and we have been doing a lot more. Now things have been pretty great recently between us but now he said this. He told me he has a hard time cumming from having sex with me because of it. In the past he's asked repeatedly for an open relationship and pushed me really hard to have a threesome which we've never done because I'm very uncomfortable with it. I can't stop thinking about what he said and I feel so disgusting and ugly. He said it so casually while we were cooking breakfast. He always tells me I'm so beautiful and smacks my ass and grabs my boobs constantly. He asks for sex or blow jobs pretty often so it surprised me a bit, but I can see it because sometimes when we're having sex it just feels like something is unexplainably wrong. I feel so ugly and I don't know what to do. I want to go to the gym but that won't even change anything. I just want my boyfriend to see my sexually attractive I mean really how pathetic do you have to be to sit and wish for that? I feel so gross and disgusted in myself and how can I really enjoy sex or want to do it now when the whole time I'm going to be thinking how nasty I am. I feel so embarrassed to cum while we're having sex because I feel like he really doesn't want to do it. This has really ruined the way I feel about myself and I can't stop sitting here and thinking on it. What can i do to fix this? I had just recently been workin very hard on my confidence and just like week had the feeling I was exactly who I'm meant to be but now this has made me feel awful. I'm at such a loss. I want to bring that spark back I'm so ashamed. I'm only 22 years old and so is he.