You've already lost one child, and I hope that you will not lose another through abortion. The grief is the same.
First of all make sure you are pregnant. If you aren't, then you and your bf have a chance to reconsider trying to have a baby. If you are, go over it with him- remember it's a life-changing event and it's normal to have second thoughts

, but since this baby was wanted you may have already developed some kind of bond with your son or daughter. No force is stronger than a mother's love for her child!