How Do I Tell My New Dog That We Have To Put Our Old Dog Down?

The day is coming. My chocolate lab, Mickey, is taking his last lap. He's been in our family for the last 14 years and his last check up did not go as well as we hoped. Mickey's eyesight is going, his hips are failing him, he's riddled with benign lumps, and now he's diabetic. Which what the fuck, who knew that was a thing? I told my dad to stop feeding him human food but he wouldn't listen. Now he's to blame for my dog's and potentially my own diabetes. Vet said we need to make a decision soon. 

Luckily for Mickey, his last few years were spent with our new dog, Avon. I don't call them brothers because I'm not one of those creepy people. Also, they lick each other's dicks so it'd be inappropriate to label them in that fashion. Partners maybe. 

Avon is a pit bull my brother rescued when he was at college. He didn't tell my parents he had a dog until he graduated and it was time to come home. My mom told him he'd have to move out if he brought the dog with him. Joke was on her because he did bring Avon home, and it was her who moved out eight months later after my parents split up. 

We're pretty sure Avon was used as a fighting dog. He has a bunch of curiously placed scars on his face and intimacy issues. Well, he pretends to hate love. Avon looks away whenever you show him affection like he's not enjoying it but the second you walk away he comes back for a second helping. You couldn't get him to bite you if you tried, and trust me I've tried. He's a mush.  

We learned early on that we weren't allowed to walk Mickey and Avon separately. Avon would lose his ever loving mind whenever we took Mickey out without him. Yelling, squealing, yelping, made a whole scene. It's just a theory, and a sad one at that, but I think whenever Avon's old dog friends were taken away it meant that they were going to fight and wouldn't be coming back the same if at all. Which begs the question, what the fuck are we going to do? 

Mickey's going sooner rather than later. He can't take two steps without being out of breath. When we take Mickey to the vet for the final time is Avon going to think that we had him killed in a fight? I can't exactly explain to Avon all of Mickey's medical conditions. 

This sucks. It's the first time I've been old enough where I felt the responsibility to be there when they put my dog down. I'm going to be a wreck, Avon's screams on the way out won't help. The only logical solution I can think of is I have to get another dog. New rule of two. I must have two dogs in my house at all times so the eldest dog never feels sad or lonely.