Concerned Girlfriend

Maria
My boyfriend just found out he may have a child by someone he used to mess around with a few years ago. All of a sudden he wants to step up and be there for her (although she is not interested in him coming back into her life) but they are making arrangements to figure things out for the baby. She is seeing someone and is not particularly interested in letting him back in the child's life because he was never there. I feel some type of way because this will effect our relationships obviously... he wants to know if I'm going to stay by his side if he finds out its his. Should I? 😶