Fucked My Sister Once, Never Let Her Know

When I was 16 my sister was 19 and was quite the slut around town. Some guys I hung with were older and one time back then they had a slut blindfolded, her dress pulled up covering her head. She was bent over and taking cock in her ass or her pussy. Her big tits were hanging down. I went in and took my turn, in fact twice, once in her pussy once in her ass, squeezing her full tits the whole while. It was my first sex, and though she didn't know it, and quite frankly I didn't suspect until after, it was my slutty sister. The guys honestly didn't know she was my sister.

I've never told her, it's been 6 years now, she found a really stable guy and (I think) intentionally got knocked up by him. She's now married and has 3 kids. She's put on weight, not as attractive as she once was with her svelte, hot body. But she'd be mortified if I told her that I had my first fuck inside her and my first anal in her.

So I don't tell anyone, but I think about it everytime I see her. I wonder if her husband pops it in her ass often.