You have to do what feels right to you, and ultimately what's best for your unborn child. That includes considering what raising a baby might be like without his/her father around. I'm very sorry you are going through this, I've been there and I know how hard it is to make that decision
You've also got to understand how your fiance may be feeling right now. He's made it clear that he does not want this child and does not feel ready to be a father, but the decision is in your hands and he feels helpless. The best you can do is tell him how you feel and hope whatever you decide that you two can work some kind of plan out between the two of you.
Having a baby is such a life-changing experience and I think sometimes, as women, we forget that once we become pregnant. All I could think about is having my baby. Seriously think about the sacrifices you would have to make by having this child. Can you afford it on your own? Will your fiance pay child support if he breaks it off with you? Have you finished school? Do you work? Are you financially stable enough to afford child care? What government programs are there in your area for single mothers? Do you have a supportive family to help you through this?
I know this is by far not the case in most situations, but my husband (boyfriend at the time) told me it was him or the baby as well... we are now married and have an 18 month old son. If he was going to be supportive the first time around, what's stopping him this time?
Good luck and I hope you reach a conclusion together that you are happy with.