What would you do??? Help please!!

Okay a little background I've been with my man for almost 2years and we have been TTC for months I found out I have endo so I got the surgery and now have been trying for about 3months since with no luck. Well he just got a FB message saying he might be the dad to this little girl cuz he had a one night stand with the mother about two months before I met him. He doesn't know I know and wants to know more I guess before telling me because he doesn't want to hurt me but I found out. This is killing me right now. I feel like GOD is punishing me. I want to start a family of my own with the man of my dreams but I don't k ow how to handle this. Please help!