At the age of 51 you couldnot get the courage to ask for a fuck, time to forget your fantasy. On top of that its a 60 year old lady, add to that your aunt. Couldnot you have a weird fantasy? Even if she allows to duck, God forbid, use KY Jelly. In case her pussy has dried and lacks natural lube, you will end up with all blisters.
Waiting for 15 years, I love you man. You sure have a wild fantasy running in your head. Time to wake up and smell the coffee. The reason you couldnot make a move was your conscious. I appreciate your conscious was right, let it stay in that way.
Come on, she is 60 years old, almost ole leg in the grave, why bring both the legs together, spread and enter there? Let her have some peaceful time.