Hey, first off...Congrats on the pregnancy! I'm sure it's going to be awful tough being a single mother, but look at it this way. If he was around he sounds like quite a jerk and I really don't think he'd change a diaper, wash a load of clothes, or try to help you in anyway it would only be more work for you if he stuck around (and who knows for how long). So in the long run as long as that baby has his/her mother, he won't need him as a father (if you can call him that, sperm doner maybe.), and you don't need him. You obviously already care for this baby, so you'll be fine! Keep your chin up!
-hopefulmjz