Help!

So I've been seeing this guy for a while now and we've gotten really close. Today I was hanging out with him and he mentioned that he's gonna find out if his ex girlfriend is having HIS baby next week. I already knew that she was pregnant and that there could possibly be a chance it's his but I'm just not sure what to do anymore. He's reassured me that they're not going to get back together regardless. So I guess I just want to know what it's like to date someone who has a baby with someone else. Is it worth it?