I Hate Myself so Much

I knew he was cheating my boyfriend went to go shower and he left his phone and I went on his Facebook and he is messaging a girl she's sending him hearts he asked her if she still lives in the same place and he puts that he likes what she says and then she asks her I'll stop by if you want or maybe not it doesn't seem like she does because I guess she didn't reply right away . He told me yesterday one girl told him she loves him and the other said she misses him he said he isn't cheating or that he talks to her and I saw he is searching his ex everyday . I went to Vegas twice I drove with my sister 4 hours away I got hotels that I paid for he doesn't have a job and I buy everything how can he look me in the face and tell me he isn't cheating again . He doesn't post nothing about us I lost friends for him I lost myself I don't know what to do I feel like we have to break up but how I do everything for him he talks to her he is seeing her obviously he is . I cheated once but I didn't keep doing it like he was and I didn't move in with the guy like he moved in with her for a year .she has kids and he is messing with her and lying to me about it he told her hat he is going to school to pick up a certificate . Things aren't going to get better why do they cheat with a good person why can't guys be happy with the person there with