This story started to develop last year to me, my sister started telling me how she had gone off sex and was sick of her husband trying it on but she still loved him and couldn't live without him. She said she was worried about him going elsewhere but didn't know what to do. Nothing more was said and I thought things had got better. Easter last year the group we swing with decided to have a day on the drink in Southend. I invited my sister and her husband Lee thinking it would do them good to get out and chill. After about 2 hours my sister disappeared when I spoke to Lee he said she had gone home and would I minded if he stayed with us as he needed to unwind. I replied of course not. As the day went on Lee opened up about how he loved my sister but he had needs in the sexual department and was sick of playing with himself. About 7 o clock it was suggested we went somewhere to party and it ended up we would go to ours to continue the party. We all got the train and an hour later we were all at back at our house. There were 4 couples, 5 single men and Lee. The men got drinks at the local shop & we ordered pizza to eat. About 10 two of the couples left leaving only the people I had slept with except for Lee. The talk turned very quickly into sex, Lee looked a bit lost but I put my arm around him and kissed him on the cheeky. Steve (my husband) said to him, things are now going to warm up if you stay what ever happens stays here or you can leave. Lee looked a bit lost then Steve tossed a coin and said you got tails you get Rachel first. Lee looked at us & Steve said it is up to you, but all the men here will fuck the two women, all done by tossing a coin. I stroked Lee,s cock through his trousers and said I think part of you wants to stay. I said make your mind up quick as I would be naked in about two minutes. He looked bewildered as Steve unbuttoned my top and pulled my bra up exposing my breasts , I felt his cock against and said I think you are stopping. My friend Julie was quickly topless and Lee didn't know where to look. Steve said right men in the kitchen and let's toss a coin to see who gets who. Myself and Julie went up to our bedroom stripped off and got on the bed. We started kissing and playing with each other. After a few minutes we were both wet when two men walked in and joined us. The rule was they could fuck us but only come in our mouths or on the towel beside us, our pussy were to be saved till we went back downstairs. Myself and Julie had both had a couple of orgasms when the third pair came up, it was Steve and Lee, I said to Lee are you OK fucking me with Steve beside you he replied I will try. I had no worries as he was quickly inside me and pounding my pussy like a man possessed. Unfortunately I didn't cum as he quickly pulled out and shot his spunk on the towel. He apologised saying I would make up for it later. The last two came upstairs and fucked us we were both a bit sore when they finished and we both went downstairs naked for a drink. When we finished our drinks we were both dragged into the living room and there was a free for all fucking us. Lee ended up fucking me twice and Julie once. About 3 in the morning I was very sore and full of spunk and said I was going to bed to sleep. I was woken up by my phone ringing in the morning it was my sister saying Lee had not come home, as I replied I felt someone behind me, they started playing with my nipples it's ok I said he slept here last night. I turned and saw it was Lee, I said my sisters name thinking he would stop but he parted my legs and started fucking me from behind. It felt so wrong but at the same time his cock felt so good inside me I was starting to say goodbye to my sister when he whispered carry on talking to her. She must of realised by my breathing what was happening but she carried on chatting. It wasn't long before he was cumming inside me and by the feel of the spunk hitting my insides Lee enjoyed it. I hung up the phone and said that was bad and got out of bed and had a shower. When I got out in went back in search of Lee but he had gone. Part 2 to follow