He had a one night stand and got her pregnant?

I've been with my boyfriend for 2 years. 5 months ago, he had a one night stand when he was very drunk. He told me the day after, I was heart broken but I love him and he promised it was a massive mistake and it would never happen again so I took him back. Then 3 months after, he got a message on facebook from the one night stand and she told him she was pregnant with his baby. My boyfriend told me and now I'm absolutely devastated. I don't know what to do, he said he doesn't have any feelings for her but he wants to be there for the baby and be at the birth too. I don't know how to handle the situation, the one night stand told my boyfriend she doesn't want me having anything to do with the baby so I feel that she wants them to be a family. I feel that they already are since he is going to a scan with her next week. What should I do? They are also meeting up sometimes to get to know each other and she is meeting his parents but he says its for the baby's sake, his mother is very excited about the baby coming, I wanted it to be me to have his first child :( Should I just dump him?He had a one night stand and got her pregnant?It seems like you're just puttin yourself in for more heartbreak later on. It's gonna be hard obviously but I think it sounds like it's time to end the relationship.He had a one night stand and got her pregnant?Hell yeah dump him! You sound like a nice girl! You dont need this! You didnt ask for it! If she doesnt want you in their lives then fuxk it! You dont have to be. You should've dumped him after the one night stand. I mean really, not even the common since to wear a condom?!? Be a tough girl and hand back his stupidity to him = )He had a one night stand and got her pregnant?yes dumo him because he cheated on you and not just because of that but do you know that he will have to pay child support to her till that bay is 18 yrs. old hope you just get rid of the headacheHe had a one night stand and got her pregnant?
First you should really just talk to him. If it doesn't go well, I'm sorry I think you should.