I know this is an older thread but have you considered sitting down with a paper and pen, ponder the situations where the comments are made and write a little script of what to say? Memorize it and use it when it comes up.
Prior to my drug use I was a hard nosed ***** about addicts and abusers. The husband and I were foster parents and had first hand knowledge of the things that kids go through. It took a lots of change in my heart to realize people make mistakes and bad choices but that it doesn't define who they are. I learned all this before my stint with drugs! I then of course used the drugs to kill the emotions that I had to deal with from caring for those hurt children! So yeah that didn't work for me...you live you learn!