I have to wonder how he contracted it to begin with, when she wasn't infected... I assume he was cheating. I have a hard time wrapping my mind around the idea that he cheated on his wife, contracted HIV, and his wife STILL stayed with him. I understand doing it for the kids, believe me, but that is insane. This whole story is just crazy.
Also, I believe I would probably kill him too. With something heavy and blunt. Aluminum baseball bat, possibly.