Plump s*s SeXStoRY

Well I guess we'll start with describing my s*s, who I dearly love and I really have no regrets about what happened because it was completely innocent. Her name is Julia and she's the awnry type. At about 5'5 215 she is quite voluptuous in a Latashay kind of way. Beautiful, large, round and very "scrunchy" big aureole with thick nipples resting atop two creamy melons, a bit of a belly nicely counterbalanced with a gorgeous bubblebut. Our first encounter happened when I had a friend over to visit one day. This friend's s****r also had very large breast, real pendulous hangers to be exact. All the neighborhood gang would comment on the size of our siblings breast. Anyway my friend got kind of frisky with my s*s. She fought initially then kind of gave in to his groping. He pulled her shirt and bra up exposing her wondrous orbs. She didn't seem to mind that I was looking at her gazongaz so I went for it and reached out gently pinched her nipples and by this time my friend had her pants off and his finger in her inviting pussy. I guess she came and that was that. She warned me to never tell mom and dad, which I wisely took to heart. It was some time before anything else happened, outside of some minor voyeurism and exhibitionism. In fact, she was married now, and had a house. I was 15 at time and partied of course. Well s*s and her husband also partied and I spent many a weekend night partying at their house. We would play cards and such, some times toying with the idea of playing strip poker when one of Julia's girlfriends would come by. Julia always avoided the subject and I was stoned horny teenager just along for the ride. Well one night I was over at her house, with no additional friends. At some point after a couple of joints of really tasty Columbian Redbud ( remember that shit!) her husband informs me that he wants me to quietly enter their bedroom later and watch him and my s*s fuck, I was oddly curious why so I chilled and waited to see if this was gonna go down. I got drowsy and went to lay down, secretly hoping something would happen. My rather large, for my age cock, was very hard. I was mildly proud of my big uncircumcised cock. The sound and steaminess of bodies writhing together began to fill the air, so I snuck into the room and watched the action from the dark corner of the room. My s****r was slick and sweaty as she rode her husbands cock which I must say was considerably smaller than mine, this intrigued me somehow. My s*s instantly new I was there and seemed to be comfortable, so slipped my cock out and began to slowly stroke it's length pulling my foreskin back and forth over it's head, it was so erotic in the most a****listic way. When they took a break, my s****r approached and with the wildest look in her I asked me if I wanted to fuck her...whoah I nearly came right there but I didn't and I turned her offer down, which I sometimes just wonder what if...by the way my s****r is sterile. What did happen after I backed down was cool anyway. We all went into the living room to get high, which was nice because we all remained naked. My s****r insisted that I get my cock hard so she could what looked like. I showed her my cock and she freaked and immediatley started shoving down her throat, her husband's eye's bulged as did my cock. She stopped and went doggystyle to the floor as her husband mounted her and I slid underneath her to watch the penetration and her giant fruit sway. Nothing else happened but I still wonder what if and I wonder if she wonders what if..I've never talked to her about it but at 47 I wonder if it's time to clear the air.....any advice from anyone.