Are you fucking stupid? Why would you want to have your ex's baby? Seriously. You would never get rid of him. He would forever be in your life. I want you to remember your ex; remember every nasty thing he did, every nasty thing he said, each horribly irritating habit he had. That's what you'll be putting up with for the rest of your life.
Think about the baby. Those beautiful eyes will look up at you someday and ask why daddy isn't around. Then you can look into those sweet eyes and say "hey, I just wanted to get laid again." There's a magical fucking moment in the making!