I just put my Karma down please help

[Dillonious]

I have loved and lived with a german rotti named Karma, I took her from a so called breeder who was treating the pups poorly.I did not think I had room for her in my life but the guilt of her situation overcame me and I took her in.
She has had some kidney problems and 3 days ago she stopped peeing/pooing and couldnt hold even water down,I kept her at home for the day but the next day when things had not changed. I held her all through the night,I thought I felt her swell and she didnt sleep much had interupted breathing and was in severe pain.I took her to the vet and they immediatly xrayed her,her bladder was 10 times the normal size it was so large part of it was swollen under her ribcage and she had a stone in her kindey,she was an older rotti and had damage to her back knees tendons. The vet said her bladder was so swollen that she may even if treated, become incontinet,or her bladder walls may be so damaged that she may rupture or be partialy rupturing as we spoke. I talked to everyone in the office that day and they kept telling me the same thing.
So I made the decision to put her down,as she was passing she urinated a foul smelling mix of blood and urine,I was horrified wondering and still am if I should have just treated her for the infection and had her given a catheder or somthing,they said her bladder was sooo swollen and most likely infected thats she may of burst when she died?
I lost my folks when I was young and have never developed another long lasting friendship or love since,never had a puppy from begining to end so I apologise for seeming so sensitive,but I am lost and feeling like I killed my best friend,when I felt I did it for her cus bringing her home would have just been for me
I just wonder if anyone has had experience in this situation or knows what kind of pain and damage a streched bladder like that can do ...did I help her or rob her of morelife?:sad: