I also lost my 16 year old to kidney failure....it was the most painful thing Ive had to go through. We struglgled for a week and she one day looked at me and I knew she was in too much pain and was getting worse everyday, we had to make the painful decision to let her go and be in peace. It was hard but I know she is in a better place and not in pain anymore. Its been a year, I still think about her everyday.
Just remember how great of a life she had with you, the good times you shared...she was a very lucky girl to have you save her and give her the life she deserved. It takes a very special person to take in an abused older dog. My thoughts are with you