Wife with her mum and stepdad

I have been married to Sandra for about 6yrs. Our sex life has been great and no problems. I have asked Sandra if she would fuck another guy and let me watch. The usual answer is NO.
Sandra was asked to take holidays as work was slow. She told me she would be on holidays from next Friday.
She also asked if i could get holidays but i told her work was really busy and i could not get any time off.
When Monday came around Sandra said she was going shopping with her girlfriend and maybe Tuesday.
Tuesday nite Sandra told me her mother was coming to visit so she would be home.
I had not seen her mother for about 2yrs so i told my boss i had to go home at lunch time and he let me go.
At lunch time i signed off and went home. When i got home Sandra's mothers car was in the driveway so i parked outside next door and walked down the side of the house to the back door. As i got to near the back of the house i looked in the window and was surprised.
I saw Sandra and her mother - both naked - and kissing. I stopped and kept watching. I noticed they were both fingering each other. I was shocked at first until i got a hardon. I dropped my shorts and undies and started jerking my cock. I did not know Sandra was bi. It was a while later - about 20min later i was shocked again when i saw her stepdad come out from the front of the house and he was naked as well. He went over to the two and gave them a cuddle. He gave Sandra's mum a big kiss and he started to get a hardon. I could not believe what i was seeing. He then stopped kissing his wife and started kissing Sandra. As he was kissing Sandra his wife dropped to her knees and started sucking his cock. It was about 6 or 7 inches and it was not long and she had it all the way in. As i was watching i was jerking my cock then Sandra dropped to her knees and when i saw her start to suck her stepdads cock i cum. I kept jerking and watching them.
As i watched they both stood up and he started fingering both of them. Sandra had Spred her legs wide and her mum did the same. Her mum was jerking him off and Sandra was playing with his balls. It did not take long and both the women cum. He then took hold of his wife and led her to the table. He helped her onto it and then fed his cock into her pussy. Sandra was standing next to them and watched them fucking. Sandra had her hand between her legs playing with her pussy.
All of a sudden i felt a hand on my arse and when i looked around i saw Deb my next door neighbor. She smiled at me and kept watching threw the window at what was going on. She then took hold of my cock and started jerking it. Deb then asked me if i had watched Sandra before and i told her i wanted to watch her with another guy but she kept saying no. I was getting horny again watching and having someone jerking me off. We watched as her mum cum and her husband pulled his cock out. Her mum got off the table, kissed Sandra and the helped her onto the table. She kissed her and then kissed her boob and sucked her nipple. I watched her step dad take hold of his cock and feed it into Sandra's pussy. He slowly fed his cock in until it was all the way in. We watched until he had it all the way in and he started going all the way in and out. I had a hardon while Deb jerked my cock. I moved my hand to the bottom of her skirt and then under it and i found her pussy. She had no undies on.
As i fingered her she was so wet. I fingered her until she cum and she kissed me with her tounge. I watched for a bit as Sandra was getting fucked by her stepdad and i turned to face Deb. She guided my cock towards my cock and then put her legs around my waist and my cock went into her pussy all the way. As we kissed i watched Sandra being fucked by her stepdad until both cum. I had pushed Deb's top off and played with her boobs. It was not long and we both cum. When we calmed down Deb cuddled me and kissed me again, looked me in the eyes and asked me did i enjoy watching Sandra and i told her i did. She then asked if i enjoyed what we had done and i told her i did. After a while she asked me if i would like to do what we did again and i told her i would love to. She put her top on and left.
I got dressed and walked into the back of the house to see everyone still naked. They were surprised but her mum asked if i would like to join them - all naked. Sandra came over to me, kissed me and told me she wanted me to join them and they would have a surprise for me.