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 :S , 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!