Why i am upset that my ex has a baby on the way?

If you cared about him, it would bother you. Unless you didn't care about him at all, which obviously isn't the case. You guys broke up for some reason. You're not meant to be together and he now has another girl and they are starting a family. I think she may be jealous if she finds out he's talking to his ex girlfriend who he used to care for and cared about him. It didn't work out and it's hard to be friends with someone you cared for much more deeply than just a friend. It may even open doors down the road if the two of them get in to a fight like all couples do. Someone could get their heart broken. If I were you I would remember the good times and leave it at that. I would wish him well and cut all ties. That leaves you free to move on as well.