I imagined fucking my SIL while fucking my wife during our failing marriage

So the title should say it all pretty much.

Just got divorced this year by my wife completely out of the blue over a phone call (there were signs, but I didn't see them until after the fact. Hindsight is always 20/20), so everything I'm about to say I have no regrets for because in the end everything I tried to fix the relationship didn't matter anyway.

So I was married for a little over a decade and towards the last 5 years of out marriage, things got pretty bitter and lonesome-with my wife literally right next to me no less.

The very last year and a half or two, we started having sex waaay less frequently then was usual, and the normal amount we had wasn't a good amount in a month/year total either. Despite trying new things, being there for her, communicating, and indulging in only her fantasies to attempt to have more sex with her, she just didn't have the same amount of sexual energy I have, and I usually just ended up 'taking care of myself' which was sad and sucked.

So anyway, my wife did have a sister that was VERY sex positive, forward, open, and more comfortable with her desire to have sex and want sexual stimulation than my ex-wife did. If you talked about anything sexual in the vicinity of my ex-wife, it made her "uncomfortable" and she usually left the room-even if it was just the two of us alone together. In short, she was a fucking prude.
Getting back to my ex-SIL though, there were countless times she talked to my ex-wife about her situations, relationships, kinks, experimenting what not. They were sisters so I guess that didn't weird my ex-wife out, but coming from me a man, and her then husband did I guess?

Well this one particular night about 5-6 years back, my ex-wife and her started talking about sexual stuff and I sat down with them to listen and partake if I could in the conversation. I had to let them do most of the talking you see cause again as I said before, If I mentioned anything sexual my ex-wife would get up and leave-so the fact I was able to sit and listen was a milestone in itself.

So my ex-wife and ex-SIL are talking and the topic of swallowing cum gets brought up. My ex-wife almost immediately gets repulsed and starts saying 'how could you do that, its so gross, why would you even think to do that?!' on and on and on. Keep in mind, we were married 5-6 YEARS at this point and It was a task to even get my ex-wife to let me cum on her face OCCASSIONALY. So my ex-SIL starts going into detail and admits that on more than one occasion, with different relationships, she had given the guy head and let him cum in her mouth and she either spit it out or swallowed it and she stated "I try to spit most of it honestly, but seriously most of the time their cum just pretty much goes down my throat and I just swallow it anyway."

So I'm incredibly aroused just listening to this and my ex-SIL turns to me and says "you mean *blank name here* has never let you cum in her mouth or even made you cum from using her mouth?! I know you guys have sex , you've been together 6 years now." to which my ex-wife exclaims "WHAT?! NO!!!! That is SO gross! I will never let him do that!" To which my ex-SIL looks me dead in the eye and says "damn *my name* I'm sorry, I've heard its pretty much the best thing in the world next to a creampie. Sucks you'll never get to experience that."

So after that conversation YEARS ago, I would fantasize every now and then about my ex-SIL naked, getting fucked, but most importantly-what she would look and feel like swallowing my cum. Now my ex-SIL also was pretty promiscuous and wore pretty revealing clothing and most assuredly, very skimpy and minimal bikinis at the beach. there were a few times when she would come over that I would sniff her used panties and cum HUGE loads in them. I did the laundry in the house so whenever I came in them, I would just throw them in with the rest of the dirty laundry and just wash them-evidence wiped away.

SOOOOOO getting back to the main title of this story: during the last year of my ex-wife and I's marriage, sex was very infrequent and when it was done, it was just for each other to get off, there was no connection or joy in it anymore-for either side. So, during that last year of my failing marriage, every time I fucked my wife, I imagined fucking her sister. Now let me tell you, I came in my wife all the time-and it was nice and all, but when I came in her balls deep and imagined I was cumming inside her sister instead with all the fantasies I had built up in my head about my SIL over the years-definitely helped we had a picture of us all at the beach together with her in this skimpy red high waisted thong bikini I could look at while fucking-those were some of the biggest, fattest loads I have ever dropped in my life, and I don't regret them at all. With my ex-wife bent over the bed in doggy (she didnt want to face me during that last year of fucking, so I'm sure she was imagining someone else fucking her too), pulling out and watching my fat thick load running out of her and down her legs, it was very satisfying.

Always wanted to see my SIL naked still, and I know she did a boudoir for someone close to 10 years ago, but I have never been able to find it.

Thanks for reading if you got this far, I just had to share this with someone.