Advice

So I just found out from my boy friends ex that he has slept with her 3 different times in our house in our bed while I was at work, she only told me bc apparently he told her he was done and he wanted to be with me and I guess that pissed her off. Apparently he loved her alot and that's why he cheated bc he will always love her, he would always text her saying how it should be her there and not me. What should I do? I mean it's not like he's going to just stop thinking about her right?? Or stop caring and loving for her right? Even if he does say they are done? Would it be stupid to give him another chance. I told him he had to change his number, and he did. He seems somewhat sorry, but when I ask him what he is doing or where he is at he tells me that he doesn't have to tell me bc I'm going to think what I want anyway.