My ex is pregnant and I want nothing to do with her.
What does she want to do with the pregnancy?
She wants to have an abortion
You should be there for someone if you impregnated them. Being pregnant and the decisions that follow can be incredibly difficult. If the other parent isn't there for support she may feel as she's alone and has no one to turn to.
I'm not her husband, she never wanted me to be involved, so I'm moving on.
You don't need to be involved if she doesn't want you to be, but if she asks then you should consider being there for her. She's having your child and that sounds pretty important, right?