*hug* Honor them and celebrate them... and remind your mother that you love them.
I lost my father many years ago. I'm not certain how he would have handled my transition; I imagine he would have been confused, hurt, and shouted a lot. In many ways he was very abusive to me, growing up. It took his death for me to realize just what he meant to me despite that. It took the birth of my daughter for me to realize how much, underneath the anger and despair, he loved me.
So, give your mom a big hug from me, OK? And congratulations.