For the Babies Sake?

I really think you should try to resolve this issue with your sister and put it behind you. Maybe you could talk or write her a letter about your feelings and that you are ready to move on and be sisters again. You will want to be a part of your neice or nephews life and there's no need to hold a grudge forever, especially with your sister. Be the bigger person and see how she responds. The relationship you are trying to fix is between you and your sister. Unfortunately the guy she chose is a loser, but she made that decision. Don't hold that against her. Be there for each other before something happens that you will regret. Forgiveness is a freeing experience. I wish you the best of luck and hope you get things worked out. You will be glad you did in the long run.