Cheating boyfriend

recent this week I have found out that my boyfriend, that I had been dating for almost a year, has cheated on me three times. The first two times he cheated was 5 months into the relationship and the third time he cheated was three months ago. Yesterday he told me everything, he cried, and I gave him everything he’s ever given me. I told him what I thought and walked away and that was the end of it. But today he came over to get our dog to spend time with her. But he told me he wanted a second chance. I asked him how long he’s thought about it, and he said since yesterday, saying he was in his room all day. But, looking back on it, it seemed like he was saying that just for sympathy. But I’m not sure what to do. We were talking like nothing happened, and laughing. But I feel if I give him another chance, it’ll happen again. Of course if I were to take him back, a lot of things would change, but if nothing does, I’ll automatically leave... I’m just not sure what to do