Break up

Today for the 2nd time my now ex-boyfriend breaks up with me and admitted that he had sex with someone else after just going one month without sex. Granted if the relationship wasn’t going to work out but to gas light my judgement just so he don’t have to feel any remorse for his actions is unbelievable to me. Saying that she was by his side when I was supposed to, I just feel so defeated at this point. What should I do now going forward from this?