I'm sorry you are struggling a bit with this. I know all too well about h's hanging out with a not so positive crowd. (My h hangs out with 25 year olds he met in the last few months who have never met me and post that he should hurry up and divorce me. They of course aren't married with kids).
I would say if you are okay with him taking the dog a simple "that's fine" works. If you don't want him to I would say, " No thanks." Short and simple in your response. Am I understanding that you are one who primarily cares for the dog? If so, you shouldn't have to accommodate h's request for the dog simply because it's convenient for him. They always like to have the "responsibility" when and only when it works for him.
Hang in there!
3 kids BD 12/15/13 (IDKIILY. ) Rope dropped Cirque du Soleil style D final 9-9-14 "Some people are born on 3rd base and go through life thinking they hit a triple." Barry Switzer
