Don't know what to do with the dog

He's a handful he's turning into the dog from hell. He is good if we are both around or one on one but when it comes to being left alone he's a pain in the ass. I'm tired and do not have the patience that I used to have. The owner did say that he would take him back if it didn't work out. I'm not really quite ready to give him up just yet. We will see how it goes. My sugars have been bad the past few days running around 12