boyfriend made someone pregnant

So I just found out today my boyfriend got someone he was fucking a couple years ago pregnant. I know it happens all the time but he's still friends and talks to the girl. I used to be kind of friends with her but she always flirted with my boyfriend so I ended up hating her and finding that out made me hate her more. Finding this out made me know she still likes him. I asked him not to speak to her and he agreed but then later he said she's done nothing wrong so he'll carry on, I don't feel comfortable him talking to her, am I overreacting? Sorry forgot to say she didn't keep the child