We are here to support though, not judge. All he said was that he knows she has driven their daughter under the influence. When she drove (alone) to pick him up drunk, he took over and made sure she did not drive anyone else around drunk.
I realize it is a sore spot for you, but I do suggest that it may be better to avoid making it sound like you are blaming someone who is reaching out for support for the irresponsible actions of an alcoholic.