Relationship

I don’t know what to do, my boyfriend after a year was caught numerous times flirting with other girls.. I broke up with him but he won’t go away with apologies and trying to talk to me, so I am trying to give it another chance but I get stop the overthinking when he is not texting me that he’s probably cheating or lying to me it’s affecting me on a emotional level when I try and talk about it with him he tells me he’s not and I forgive it at that moment but when I’m just thinking I can’t stop thinking... any suggestions