Stressing :/

My ex and I recently broke up for good, after breaking up several times and now I think I'm pregnant with his child. How do I tell him if I find out I am.? And does that mean I should go back to him so we can raise the child together? I really don't want to be with him anymore, we were awful together and i would be scared to bring a baby into that.. I just don't know what would be best :/ I'm scared someone please advise me.