Grow up and have some honor and respect for your family. The world was not created just to give you the instant pleasure you desire.
It is quite common to be attracted to someone who you should not have sex with. It is pretty much never a good idea to ask a family member if they want to do such a thing. She will never be comfortable around you again if you express any interest in sex, and she will tell other family members about it. It is much better for you to never tell anyone you are interested.
guess that depends on is she your real aunt.? like mother or fathers sister?
resist from making a move with her...it will cause pain in the family....