How should I react?

I'm sorry if this isn't the right group for this. My parents have been divorced my entire life and they both remarried right away, everyone was always actively involved in my life. My stepdad says he claims my sister and I as his own kids, but he never went to events that my dad went to because he hates my father. My parents get along fine, my mom even talks to my stepmom. But he's missed our school concerts, sporting events, graduations, and many more important things. My baby boy is due in under 2 weeks, and I live an hour away from my mom and stepdad, my mom just told me that my stepdad doesn't plan on going with her to see him at the hospital because my dad is going to be there. This is their very first grandchild. Should I say anything? I'm very upset about it but I don't want to start something for no reason.