Bio dad wants to meet the kids after being absent the entire 5 years
I've been with my gf for almost 4 years and we have a 2 year old son as well as the almost 5 year old twin boys. They have only known me as a father as their dad wasn't there when they were born/in the nicu. He spent a few hours over the course of 3 days or so a few weeks into the twins life and nothing since then. He just recently started expressing interest in getting to know the boys. He is currently in a mental home for burning his sisters apartment down because he didn't want to live there anymore but will be getting out soon. My gf doesn't want to hinder him if he wants to really be there for them with 100% effort but I am skeptical and a little hurt as I was the one supporting the family building bonds with them comforting them, being there for them in the emergency room late nights. What should I do? I know what I want to do but what say so do I really have?