Feeling like giving up on Alcoholic Father. Any words of wisdom?

My father has been an alcoholic my whole life. Hes been in & out of my life since I was a little girl and I have always been the one to defend him and believe in him..but I'm starting to loose hope. He was in jail for 6 months 3 years ago for multiple drunk driving incidents & has been in and out of a few rehabs since and I was under the impression he was getting better. I'm pregnant, with his first grandchild ever. We seemed like we were getting closer for the first time in my life, just a few months ago I wrote him a long e-mail telling him how scared I have been about loosing him and how his alcoholism affects me and that is the FIRST time I have ever reveled how I felt to him about any of this, all he wrote back was "I'm sorry I dont know how to respond to this." & since then hes been more distant..when he does call he wants to get off the phone right away and I even called and left a message for him last week that he was going to be having a GRANDDAUGHTER and he didnt call me back for 2 days. I just found out from my grandmother that hes in trouble again. Got into another accident with his work truck drunk & to make matters worse fled the accident scene. I know hes going to go back to jail, everyone told him how lucky he was to only have to go 6mos last time with all the charges he had against him. It truly breaks my heart that he most likely wont be there for the birth of my first baby, & didnt even care enough to think about that when he got behind the wheel drunk..AGAIN. I feel like I'm ready for the first time in my life to give him the cold sholder, hes really hurt me & it seems hes never going to change no matter what the cirstances. But at the same time I know how much that would hurt him, I've always been "Daddy's little girl" no matter how disfunctional hes been, hes told me before that I'm his only reason for living. I'm just afraid of loosing him. How do I deal with this!