He cheated, I left him and I just found out i'm pregnant with his child?

3 weeks ago I busted my man of 1 year cheating on me. To make a long story short I left him without a trace. To me cheating is the ultimate betrayal and is hands down unforgivable. There is NO excuse to cheat. Anyhow, I just went to the doctor yesterday to get checked for STD's and wouldn't you know I found out I'm pregnant from him. I don't even know what to do or say here. I want NOTHING to do with him, but not I'm pregnant with his child. What do I do?