I Don't Know What to Do

Ok, I've been putting off taking Jedi to the vet, one because Jon freaks out when I spend money on animals and 2, I just didn't want to hear what they had to say about his leg.
We knew he had arthritis, but in the last 6 months it has gotten worse.

I took him in and He has a luxating patella on both of his hind legs. The doc looked at him and there is a scale on how bad the legs are.
One they stay in socket, but you can manually push it out easy.
Two, it stays in socket, but comes out on its own
Three, stays out of socket mostly, but will go back in sometimes
Four, stays out all the time

One of his back legs is a 4 and the other is a 3.

He said he is too far gone for surgery and realistically too far gone for even the glucose medicine. He said basically just make him comfortable. I asked if he suggested putting him down, but he said no.

Here's where my problem lies. My dog is in pain. And basically he was just telling me to give him some baby asprin if he seems to be having an unusually bad day...

I just don't know what kind of quality of life that is... don't get me wrong I DO NOT WANT TO PUT MY DOG TO SLEEP. But I also don't want him in pain all the time.

Right now he walks around on 3 legs, so what happens when his other back leg gets to a 4?

I don't know. I'm confused and a little emotional about it.

Advice from anyone??

You can read about his problem HERE