"having to hold your best freind while they slip away is 1 of the hardest things I have ever done"
+1. It has been 6 years since I had to say good bye to my No.1 fishin' , walkin' and all over best bud. She was 9 years old and had displasia since she was born - it was so bad she dislocated her hip playing catch in the back yard when she was a pup. Vet said at the time it was the worst case he had ever seen in a pup that small and young(Keeshund / Shetland collie cross). Fortunately meds kept her going with a good qualifty of life for 8 years after that. But once she couldn't do the stairs, go for walks or run in the snow (her all time favourite, next to swimming), and then started to loose control of her body functions we knew it was time to say good bye. I beleive it was the right decision... but I will never forget the ache from having to do that and the silence in the van as the family drove back from the vet .
We chose not to get another, mainly due to family commitments.
To pile all those other issues you had to do deal with on top of that - ouch. Not sure what to say other than - condolences on your loss; think about having your sons tonsils removed (made a WORLD of difference to our two), and..................things can only improve from here. Whether you decide to get another dog or not - you will know what is the right thing to do one day, and will do it.
Good luck to you.