TroubledSister,
Please don't cut off your nephew from contact. You may be the only stability he has in his life. Sending him cards is a nice and supportive gesture. It keeps the line of communication open between you and your nephew.
I think your nephew is going to have a lot to deal with having an alcoholic, narcissistic father in his life. My aunt was a life-line for me.
Love,
Lenina