This occurred about a year and a half ago. My wife and I had decided to separate (a joint decision - we just grew apart). It was all fairly amicable and I still lived there while I was looking for a place to stay.
I have fantasized about her fucking other men; which she did a few years ago, on a couple of occasions. After a while this just helped to fuel my fantasies and periodically became part of our sex sessions, along with a large dildo, which we used to pretend was another cock fucking her.
After we decided to split up, we still slept in the same bed and still had sex but less frequently. This was hard, so she decided we could still play with each other but I could not fuck her, this was OK by me because I loved licking her pussy and she responded eagerly. It was while we were having one of these sessions that we started talking about her having a pussy full of cum, what it would feel like having her panties sticky with it, whether I would like to see it, maybe even eat her out. This used to get us both very hot and resulted in some great sex (no fucking).
About a month and a half into this arrangement we both started going out separately. It was about this time that she met some guy she started having sex with, she would come home from being with him and tell me all the details (apparently he was very well hung). She would also leave her cum stained panties on the floor for me to find. (I think she was leading me in a certain direction I was happy to go in.) They could only fuck in cars or other friend's places; they didn't have anywhere else to go. These nights got her hotter and hotter, and in the mornings would love to have me finger fuck her to many great orgasms, even though I could feel her pussy had been well stretched.
One day while we were very randy and I was fucking her with her dildo, licking her pussy and talking about it being full of cum, she asked if I would really like to see her pussy full. I nearly came on the spot. She asked if we could organize it so I went out and he could come over, after he had finished she would send me an SMS to let me know the coast was clear. We were both very turned on all week
Just thinking about it. Finally the night of her encounter came and we both got ready for the night (me to go out her to get laid). While she was getting ready I took some pictures of her (she was hot and wet), she even wore a pair of see through panties and bra I suggested she buy.
At around 8 p.m. I went out. The time just dragged on, 9 p.m., 10 p.m., 10.30 p.m. At around 11.15 p.m. my cell phone went of, I had a message. I M READY.
When I got home the music was loud, she was having a drink in the kitchen and gave me a great big at me as I walked in, her hear was messy and cheeks flushed.
"Would you like some wine?" she asked.
"Yes. How was it?"
"He came in me 3 times. The first was soon after he arrived, the last just before you got home. I'm soooo randy."