Need advice

So I’ve been with this guy for almost a year now and two weeks ago he said that he was on something(don’t remember) he messed around with a girl and now she’s pregnant. She’s keeping it.He says he still loves me and still wants to be with me and I love him. But that brings a whole situation into the equation. I’m not one to leave people or give up on someone. I’m one to give chances and forgive. But I have a big choice that can make or break my life of staying and possibly caring for his child or not continuing to be with him( which I won’t get over him-this I know) but still be there for him. I’m stuck and I don’t know what to do. I love him but I don’t know how to handle it.