*Your DH is prepared to break your heart.
That alone would be the end for me.*
I agree. To me, this isn't a question about dogs. This is a question about someone who is meant to love you, asking you to break your own heart over something that has a finite end anyway. This dog must be 6 or 7 years old by now, based on the details given. If that's accurate, the chances are this dog has maybe 5 or 6 years left (sorry OP).
Who chooses breaking the heart of someone they love over 'putting up' with the dog for a few more years? Especially when they knew about the dog going into the relationship.
I am not a cat lover (sorry cat people); living with one annoys me for all sorts of reasons & I am allergic to them. There is no way on earth I would expect a partner to give up their cat because I didn't like it. No way. In fact, someone that did give up their beloved animal so easily would be a total turn off for me.
All the talk of people being 'above' dogs drives me crazy. It is not a bloody competition. Dogs (or any pet) do not choose to live with us. We make that choice for them and are, therefore, under a serious obligation to look after them well to the end of their days, barring something very serious going wrong. Anyone who takes on that kind of commitment and then gives it up easily is showing how lacking in moral fibre they are - to me anyway. It would cause me to question what else they were going to give up on when the going got tough.
The old saying comes back to me 'when someone shows you who they truly are, believe them'.
Good luck, OP. Your husband has dealt you a shit hand here xx