MIL Advice Needed!

I want to start this by saying I'm not a very forgiving person. I used to be, but I've just gotten hurt by repeat offenders one too many times, so I no longer forgive easy. This may be to a fault, though, which is why I'm looking for some outside opinions. Three months ago, I got into a pretty nasty argument with my mother in law because she wanted me to terminate my pregnancy so my brother in law's girlfriend can be the only pregnant one. My mother in law knew my husband & I were actively trying before girlfriend was even in the picture, yet she called me selfish for keeping my pregnancy and attempting to "Ruin their special moment." Since then I have gone completely no contact with her & we have even moved states to keep her away from the baby when he's born. She has recently texted me looking to reconcile, and I explained that although I hear and recognize her apology I can't forgive her for what was said, and if I am ever able to it will take a long time. She is totally refusing to accept that & my husband thinks she should be allowed in our son's life because it was just a mistake, but I can't see forgiving the Grandmother of my son for saying he shouldn't exist, that I should've terminated him. Am I being too harsh or am I in the right here? I know that a lifetime is a long time to keep someone away, but my son can't miss someone he never knew and I don't want to introduce her to him just for her to do something similar again in the future. My husband is convinced that his mom will clean up her act, but for all I care she can spend all her time with BIL's baby and have the life she wants where my son doesn't exist. Thanks for the read, sorry for length.