What do I do????

A little over 3 1/2 years ago, I was in engaged to my daughter's "dirt bag" and pregant with my daughter.  We were on the way to his dad's house in Timpson TX for the weekend and he said before we get there I have to tell you something.  It's a small town and you never know who you are going to run into.  I was like okay no big deal.  Then he proceeded to tell me a story that would knock you over with a feather.

He started to tell me about an ex girlfriend that he was with when he lived up in Timpson.  He went on to tell me how they had a good relationship but eventually she turned crazy.  Well you always take that with a grain of salt because exs are always crazy and there are reasons why they are exs.  He told me they had a son together.  I was like huh....what........why haven't you ever told me about him?  He said she had cheated on him, was horrible, etc.  He said he tried and tried to see him but she always would hide their son from him and then she up a married a buddy (who according to him was a guy she had cheated on him with) and they moved to Nebraska.  He lost track of them and then one day she tracked him down and wanted him to sign his rights away.  And he did....I just sat there in disbelief.  Who walks away from their kid?  He said he felt guilty and thought about him everyday.  He said her husband was a good guy and he would be a good dad.  So now this buddy who had betrayed him was a great guy......What do you do with that kind of information?

Well life went on, we had Katilyn, and then our relationship went south.  He started saying he wished we wouldn't have had Katilyn.  He didn't want her and his oh so famous words of I want to sign my rights away. 

I struggled with what to do in the meantime he disappeared from Katilyn's life.  Eventhough I had friends and family giving me advice....no one understood how I felt or what I was dealing with because who ever really ends up in this kind of predicament....me of course. 

Last February I got "curious" and thanks to the help of the internet, I found the mother of his son he walked away so many years ago.  We talked for hours on the phone, we texted, etc.  She helped me find answers that I never thought I would find out.  She for the longest time didn't want me to let him know we had found each other.  Then last night while we were talking she said tell him.  Let him know that we talk and know each other.  I just sat there in shock.  What do I do?  How do I tell him?  Do I just text or email him and say hey buddy...I've met your ex and the son you abandoned?  I don't talk to him enough to drop that bomb. 

I don't know what to do.......AHHHHHH