5 year fiance caught cheating.

Guys my future husband is just not who i thought he was. He is a terrible liar. I just found out last night from the girl he was cheating with. He lied his name to this girl. He told this girl that i was in China and that he had broken up with me to be with her😂. Apparently he has been having unprotected sex with this girl. And it hasn't been just myself and this girl, she was also bein cheated on with some other girl. Therefore its a chain.I showed him that i now know everything and he began to apologize. I don't even know what to do with him. I'm just so worried about all the unprotected sex we had😩😩