My Aunt
I really want to have sex with my aunt. Let me describe the situation and maybe you'll understand.
My uncle married a woman a few years younger than himself. My uncle is only 13 years older than me and his then wife is 6 years older. When I was about 14/15 I had spent the night over at their place and I remember it well because it was bed time and I was in the living room and she came out to show me how to work the cable box and make sure I was settled. She bent over and I could see down her lose shirt at her freckled chest. Her tits were perfect and I saw nipples. That was a big deal for me at the time.
Five years ago I saw her again. It sounds ridiculous but I still call her my aunt, even though she has been long divorced my uncle. She insists that we are family and I should still call her Auntie. Now she is in her early 50's and can pass for one of her daughter's friends. She even told me that I grew up to be good looking and I'm thinking I want those nipples in my mouth.
Go for it, but be careful! You may destroy your friendship if you move too fast or are too crude in the way you approach her. Treat her as if she is a girl you are trying to seduce and you should do OK.