Get rid of the Guy forever! Make sure he supports his Child, as far as you current situation, only YOU can make that decision, it's not up to anyone else. Going forward, don't let this guy back into your life, stop being his plaything. Get some sort of birth control .
Guys 'do this' because you let them. You didn't learn the first time???? The baby is already here. The next one is coming. Why don't you figure out how to NOT have any more? Do you take good care of your child? If so, then you would take good care of the second. So having another kid isn't the issue. It's the guy who keeps knocking you up. Make HIM either be responsible, or kick him off the baby maker bus. If he isn't supporting you and the kids, shame on Him AND You!
You never know what this child could posess, greatness or grief. You terminate this person, she/he could make your life better in the futur. Stupid parents don't always make stupid children. I'm an optomist, she/he will make a difference, if not the world, but to you.
You have to keep the baby. It's your job as a mother to give your child unconditional love and care. If you give it away, think about all of the things you'd miss out in. You would miss your own child's first steps. You wouldn't be there when he first learns to ride a bike. You wouldn't be able to spend time with him at the beach. When he gets hurt, he wouldn't have you to make it stop hurting. You would miss his prom night, or first date. You would miss when he graduates High School, or College. You would miss everything regarding YOUR very own child. Plus, think about the kind of person you could make him/her. You can raise your child to be the very best it can be. Put yourself into this child. I suggest you keep the baby but it's not my choice.