I also feel sorry for the dog, but as someone who is STILL saddled with 2 of my ex-husband's dogs, I would say find a home for it. Find a no-kill rescue and explain the situation. They will find a loving home for it. The dog deserves someone who wants him/her, and if that isn't you, then you are doing him/her a favor.
As for me, I am stuck because my kids are attached and they give them the love and attention they need. So I continue to care for them. But if it was just me, I would let them go to new homes in a heartbeat.