Sorry to hijack, but it's what I do best
I have a hard time understanding how some idiot can chose drugs or anything for that matter over his/her child. I'd happily cut of limbs or step in traffic just to have my child feel no pain.
As far as I'm concerned your ex waived his rights long ago. I wouldn't worry about what he's going through because he sure didn't seem to care what you and your child were when he could have.
Plus, there's nothing saying that your child can't contact the father later in life if your son feels he wants a relationship with the man.