This happened just after I turned 18. It's absolutely true only I changed her name.
When I was late 18 I began doing odd jobs for our Aunt Grace, who was then about 50-ish and had been widowed. These jobs included a bit of gardening, cleaning the gutters, washing her car, etc. Mom didn't mind my going over there and the pocket money was good. Several months later, one summer day I was standing cleaning some leaves out of the gutter when I found I could look into her bathroom and there she was stepping into a shower. I only saw her bum but it was enough to make me stiff and I had to climb down the ladder with shaking knees, duck out of sight and jerk off thinking of what she'd shown me! I was afraid she'd seen me, afraid to be feeling so aroused and afraid I'd want to peek at her more. Needless to say I was a virgin and hadn't even had a girlfriend yet thanks to my parents' strict upbringing.
After that I began to see Auntie Grace as a sexy person though I don't know if she noticed that at first. However, since I visited her most weekends for a couple of hours of work, she seemed to smile at me a lot more and be a little more cheeky. I never saw her with any other guys but that didn't bother me. Once or twice she seemed to scold me when there was no need for it, but I could tell she didn't really mean it and it didn't last long.
By now I was masturbating several times a day realizing how good it felt and I'm ashamed to say I became a bit of an upskirt peeper, almost getting into trouble for it on several occasions. My Mom and Dad didn't suspect anything. The next few times I visited Auntie Grace I would get out the ladder and stand it against the wall near the bathroom window, hoping for an opportunity. Grace expressed surprise but I just said I might need it for some jobs. Did it come in handy!
About half an hour later I glanced towards the bathroom window and saw Auntie head for the shower. Dropping my chore, I stealthily made for the ladder and climbed the first few rungs, then peeked. I nearly fell off. There was Aunt Grace facing in my direction with her eyes shut, soaping her breasts with one hand and washing between her legs with the other. I undid my fly and began to masturbate watching her. It soon became apparent that she was doing more than soaping herself. For what seemed like a minute she was thrusting her lower hand in and out of her dark bush, rocking on it, though being above her I couldn't see any more than that; however I understood what it meant and ejaculated all over the ladder and the ground. I quickly got off the ladder before she opened her eyes and spotted me.
When Auntie Grace invited me back in later that afternoon for coffee and cakes, she seemed more relaxed and told me (as if I didn't know!) what a nice shower she'd just had. She was still in her white bathrobe, which was surprising, and I half hoped that it would fall open to reveal her. Sitting opposite me, she crossed her legs and I stole a look but didn't see anything. Then she lit her afternoon cigarette and asked me if I'd like to see something interesting. I thought she meant a picture or a magazine, so said yes. Blowing a puff of smoke in my direction with a sly smile, she undid her robe, lay back and spread her legs wide apart. She wore no panties and I blushed with embarrassment and arousal to see her open vagina surrounded by bushy hair. I felt my manhood growing irresistibly.
'Oh come on, don't look so surprised! I know you were peeping at me through the window. Go on, take a good look.'
She remained in that position for me to stare at her. Grace gave a little laugh. 'I can see you haven't seen many girls that way. Have you?' I dumbly shook my head. She went on. 'Show me what's bothering you down there,' looking at my crotch. 'Let me see you touch it'.
I was too embarrassed to do as she requested. 'See, I do it like this', she said, putting her cigaretted down and parting her private folds with her nail painted index finger. She moved it with a little circular motion over a little lump she called her 'clit' while I was mesmerized. I felt compelled to show my penis to her; her eyes were nowhere else. Aunt Grace began to rock, the way I had seen her in the shower. 'Oh, good boy,' she breathed, plunging her fingers inside her, 'do it for Auntie.' I did.
Suddenly a huge orgasm flooded over me, my penis jerking and squirting at her several times, making me feel both awfully ashamed to be exposing myself but also wonderfully proud that she appreciated me. Auntie then lay back, her eyes nearly shut and hardly looked while she frigged herself till she too came in short moans, her thighs contracting each time. I kept masturbating, my hands slippery with semen, just watching her though I could not come again for at least half an hour.
Then she called me over and we hugged and kissed and fondled each other on her sofa for a long time. After about twenty minutes I was erect again, and this time she took my penis in her hand for the first time and expertly brought me off while I inexpertly found her deep warm hole with my own fingers. We stayed like that for a long time. She made me promise never to tell anyone.