I'm so sorry for your loss :( It's such a terrible and difficult decision to make. I said goodbye to my bun in September. I felt horrible but I knew that I was releasing her from a painful, uncomfortable life. She was blind and had lost the use of her back legs. I did the same thing as you and gave her ALL the treats I could find on her last day. I'm sure Bun-Bun is thankful for the life you gave her while she was with you.
We did the best we could! I'm sure your bun had the best life too. it's so hard to say goodbye to the sweetest little furry creatures. ;__;