well i think everyone should support your decision either way. This is your baby and I am CERTAIN she has had 15+ years of a happy life. I for one would never judge you nor tell you what you should do. I am sorry your even in this situation but everyone knows they cannot live forever. Hopefully the surgery will be a complete success and she will go in the guiness book for the oldest yorkie ever and live to be 100!!!
You listen to your heart...your her mommy and mommy knows best! Anyone that judges you In my opinion is the selfish one.