How would you honestly feel about this if you were me? Am I too sensitive?

No, not at all. You're not being too sensitive. You and this guy have a very complicated past with love and trouble and ups and downs. There was obviously something in the beginning that drew you to him, and something about him kept you with him for so long, and even when you broke up, that same thing kept bringing you back to him. You had love for him, and love can be hard to get rid of sometimes. But you know in this situation you have done the right thing. And now, of course, you know that you have to continue doing that right thing - which is to stay away. You have done an excellent job of staying strong, and now that he is having a baby - your old emotions for him are being stirred up cause you know that that could have been you if you stayed with him, you could have gotten pregnant with his child. But you didn't, and he is now with another girl who got pregnant. You should consider yourself lucky. What if you had gotten pregnant right before you were planning on leaving him? Just remind yourself you left him for a reason, a very valid reason, and that even though you still have to see him sometimes, always know you made the right choice. It will only get easier from here on out to stay strong and get over him. You're doing great. Also, having another guy in your life would be a good distraction for you. It'd help you see what other options there are and keep your mind off of your ex. So if you could, I'd try and start dating again. It is the best way to get over someone.