If you don't want to marry him, don't. The baby wouldn't be happy if they knew mommy and daddy won't be happy together. Do whatever makes you happy :)
If you dont want him,then dont be with him. There's not much point to it. Be strong and be stable because i believe there are many single mothers out there who's raised many great kids and still be happy. And if you would find a great guy in the way who'd love and treat you and your baby right,then that's great.
Leave him! If he has another girlfriend, she's pregnant too & lying to you about going to work when he's actually been with her. You can find someone else to help you take care of the baby. There is a lot of men out there that are willing to be a step dad and treat you & the baby right. I would suggest leaving him and after the baby is born putting him on child support. Most males to me are just idiots. I'm sorry that happened to you! Good luck!
You answered your own question. You don't want him. He's the dad. Let him just be the dad.
There's a phrase where I live for situations like this: "Head for the hills!" If you don't want him, don't keep him! Get away and out of that relationship.