Harry, my wife Sarah, and I are the same age and all started school together. We lived close to each other, played after school together, and were a childhood threesome until our early teens when puberty hit. Harry and Sarah dated for a year before she turned her attentions to me, so Harry knew Sarah's body pretty good from their heavy petting up to but not including intercourse. The remaining two years of school, Sarah and I dated exclusively, Harry moved on to other girls, and we resumed being a social threesome and best friends. Fast forward to twenty years later in our late 30s still living in the same town as best friends with Sarah and me married and Harry married and then divorced almost a year before. That was two months ago. Over the years Harry and Sarah flirted outrageously in front of me and Harry's wife, but all in good fun, and I would tease Harry about him missing out on ultimate sex with Sarah. In bed over the later years I would sometimes ask Sarah if she wondered what sex with Harry would be like and this sometimes led to her verbally fantasizing about it whilst we fucked. Two months ago on a Saturday we three took the train into the city to have dinner and then see a play. Harry was down more than usual about the divorce so I let him walk with Sarah from the train to dinner. They held hands as they talked about the way he was feeling and the same after dinner on the walk to the theatre. After the play Harry was his old self again and we were having such a good time in a pub we missed the last train back, so we got the last room available at a nearby hotel. It had two double beds but we thought nothing of it since when he was married we shared a hotel room with him and his wife a few times on holdays together. Between us all tired from the long day and tipsy from the after theatre drinks at the pub we quickly went to sleep with Harry in one bed and us in the other. Not having brought a nightgown with her Sarah was wearing her bra and panties to bed and I was wearing just my vest as usual. Harry had sat on his bed wearing just his pants and I noticed they were tented out from an erection. When he thought Sarah was not looking he quickly slipped his pants off and slid under the bedcovers but not quick enough as Sarah glanced over at that very moment and saw his hard-on. As she and me rolled together for our usual before sleep cuddle I whispered to her, "That was impressive. Why don't you join him for a little 'slap and tickle'?" She answered, "That's the drink in you talking. You wouldn't like it one bit." As I rubbed her bum and pushed my now hard-on into her she said in a very tired voice as she drifted off to sleep, "And I might like it too much." At about half seven in the morning I woke up horny from a dream of watching her and Harry going at it next to me in bed and began playing with her breasts and nipples through her bra. She responded by taking it off and I caressed her breasts and sucked her nipples until she was squirming under me. Then I began fingering her pussy and she played with my cock. All this activity resulted in the bedcovers moving down below our waists. When I pulled her panties down she asked if Harry was awake since she was on her back on the other side of me and couldn't see him. I looked over and saw Harry awake and watching us but told Sarah he was asleep. I finshed removing her panties keeping my body so she couldn't see Harry who was now slowly playing with his cock under his bedcovers. I was deep kissing her and fingering her now wet pussy. I soon made her come with my fingers and she stifled her moans by turning her head to the wall and burying her mouth into the pillow end. Before she could recover from her come I got between her legs which made our bedcovers slip all the way off us and mounted her. I held myself up on my elbows as I thrust my cock up her and then fucked her nice and steady whilst kissing her. She was still feeling the effects of her come from my fingers so it didn't take long for her to come again from my cock. When I felt and heard her start to come I speeded up and came with her. It was obvious to Sarah that the noise we had made coming most certainly should have woke up Harry so she buried her face in my neck from a bit of embarrassment at fucking naked in front of him. After a while I had no choice but to get up from between her legs where my cock was still most satisfactorily nestled in her hot and wet pussy and relieve myself. When I came back out several minutes later I stopped short when I saw Harry sitting on our bed next to Sarah's waist leaning down and saying something to her as he stroked her naked tummy with his hand. She said something back to him in a low voice that I couldn't hear and then nudged his hand downward. He then leant down further and kissed her as he slid his hand from her tummy down over her lightly haired mound and into her cunt. As he did that she raised her knees and spread her legs wide for him. At the same time she wrapped her arms around his neck and deepened their kiss. My cock became fully hard as I watched the beginnings of their fuck. My wife of almost 20 years was about to fuck our best friend right before my eyes. I stood frozen as I watched him slide two fingers into her and then quickly add a third finger as they kissed. His hand movements quickly sped up and Sarah started moaning but before he could make her come with his hand she reached down and stopped him saying, "No. Come in me and do me proper. I want to feel you inside me." He got between her legs in about two seconds and I watched as my wife eagerly grabbed his cock and guided it into her pussy. He thrust his hips forward like a starving man and was instantly up her. He dropped his upper body down onto hers and buried his hands under her shoulders as he fucked her rapidly which was no surprise since he had told us it had been well over a year since he last had sex. Sarah fucked him back just as desperately with her feet flat on the bed leveraging her hips up into him as she fucked him back. She came only a minute or two later with deep moans and gasps of sexual pleasure. As she was coming his bum cheeks clenched several times as he poured his cum into her and her hips jerked as she received it. When their sex moans and gasps finally quieted they lay there with him on top of her between her legs and her arms and legs wrapped around him hugging him tightly into her. As they finished I quietly sat on his bed and slowly wanked my cock to relieve some of the sex pressure but deliberately not enough to come. After a few minutes they stirred and finished recovering. Looking over at me at me from under Harry Sarah said, "I'm sorry if I've hurt you but I just wanted to know what it felt like with Harry after all these years." Strangely enough or maybe not so strangely I didn't feel jealousy or anger. I just felt horny at watching my wife coming with another man so I answered her with, "No problem." And then I asked, "Do you want him again now?" She answered, "No. Not yet. I want you again first." Then to Harry, "Do you mind. You can have me after if you want." He said as he rolled off and got up from the bed, "Oh yeah. I'm going to want you again." Then he said to me, "I'm sorry if you're angry but I couldn't help myself after watching you two have at it." I told him 'no worries' and rejoined my wife for another enthusiastic fuck. We three wound up staying in bed with Harry and me switching off in Sarah for the next hour or so. Then we went down to breakfast and acted like sharing Sarah in bed and then having breakfast was our regular routine. We caught the noon train back and as we were the only ones in the compartment we talked about what had happened and where to go from there. We all agreed that we had immensely enjoyed it. Harry and me agreed we had thoroughly enjoyed watching each other fucking Sarah. Sarah said it was so erotic to have her two favourite men hungering for her and especially so when one of us would fuck her immediately after the other had finished. Its all been all good these two months since then with Harry staying over one or two nights a week and me sharing Sarah with him. And Sarah is insatiable wanting it every night or morning and sometimes both between Harry's stayovers. I have no complaints at all.