Here's a similar story. I broke up with a girl I dated for two years because she started cheating on me. Now on her defense, I had already left town for a year (I joined the Navy) and would come home for a couple of weeks every six months. We did the letter writing and phone calling almost everyday, in any case, it was not enough.
A couple of years later her brother asked me to be his kids godfather. I said yes since I was still in contact with her family (I was also still friends with her too). So one time I go home to visit my goddaugher who was upstairs with her parents while my ex was down stairs with the new boyfriend and her mom. My goddaugher's parents were talking to each other while I was visitng my goddaugher and I heard, "Have they told her?" "No, I don't think so" So I ask, "what are you guys talking about?" "Oh", one replies, "Rachel (my ex-) is pregnant and they are telling her mom".
That sucked! They didn't even think that it would bother me. It was totally unexpected. They must of told her soon after I got there, because as I was leaving their house, the grand-ma to be (who had been crying) gave me a hug and whispered,
"I really wish you were the dad". I replied, "Yeah, me too."
They never got married, but I think they are still together. The real sad thing is that when the baby was younger (2-3) I would spend more time with her than her own dad would.