What I am about to relay to you is something only one other person ever knew. In the early 80's I had just turned twenty and although I had plenty of girlfriends and got my fair share of sex I had a crush on a mates mother. She was a sexy forty two year old MILF by todays standards. There was something about her fuller figure and her flaming red hair that got my juices flowing. It was clear that she knew that I had a crush on her as she flirted outrageously with me even in front of Bobby her son and my mate. This flirting went on for months and I decided that I had to see if it was just flirting so I engineered a visit when I knew she would be on her own. Initially she flirted with me and then she stopped as she suddenly realized that I wanted things to go much further. Then it was like a switch was thrown and she was on me and kissing me and fondling my growing cock through my jeans. I was groping those lovely full tits and fingering her fanny through her panties. Carla was moaning into my mouth when I slipped a couple of fingers inside her panties and straight into her pussy. Then she pushed me away. I thought she had just had a change of mind and come to her senses letting a lad half her age help her cheat on her husband and family. That wasn't the case as she dragged me up the stairs and into her bedroom. She stood still only moving to allow me to remove her clothing. I went for the blouse and the bra. Once they were off I was fondling and sucking her large stiff nipples. Carla was panting and groaning again. Then I was still sucking her nipples as I released and dropped her skirt to the floor. I could see the cesarean scar where she had given birth to one or more of her three children. I kissed the scar and then on her pubic bulge through her panties. As I pulled the panties down her bush of red hair sprung into view. Then I was licking and sucking on my mates mother's pussy. Sucking the plump pussy lips into my mouth before sucking long and hard on her clitty. Carla was moaning and groaning all the time as I licked and sucked. Then I was ripping my own clothes off as Carla climbed on the bed and spread her arms and legs wide. As soon as my clothes were off I was on the bed and slipping my cock into those plump lips right up to my balls. Then we were fucking like ravenous animals at a kill. Carla's groans became louder as I piled into her pussy and then she went stiff. She had just come and I was at the point of no return. Suddenly Carla called out for me to pull out. She was too late as spurt after spurt of my semen filled her pussy. Afterwards as we lay together she looked worried and told me that she was not on the pill, she couldn't take it, so she and her husband used condoms. I told her I was sorry, but I couldn't stop. About forty minutes later we were fucking again. This time doggy style. I really loved that, holding her tits as they swayed and plowing into her pussy. I had persuaded her to let me go bareback as I had already delivered a large load into her pussy, and what harm could a second load do that the first didn't already do. I delivered my second load and once recovered Carla told me to leave as it was almost time for one of her brood to come home. After that day Carla kept up the flirting and we continued to sneak around and screw whenever we could. I thought I was in love and when I told Carla she told me that any more silly nonsense like that and she would stop seeing me. Then a month or so further down the line my mate told me that his mum was pregnant and he was excited to have another sibling. As soon as I managed to get time with Carla alone I asked about the baby and she openly told me that she thought that it was probably mine. In case I had got her pregnant she punctured one of her husband's condoms with a needle and the next time they had sex it split just as he came. He thought it was his baby. It didn't stop Carla and I from fucking every time we could. Sarah was born and for three months I had no chance of getting with Carla. When we did finally manage to get together I fucked her brains out and that rebooted our affair. After that Carla insisted that I always wore a condom. If it was the only way I could have her fanny then I had to comply. Our affair continued over the years and I remained friends with Bobby and became god father to Sarah. I watched her grow up and even became friends with her. When her father died in 2011 I comforted Sarah and Carla at and after the funeral. My affair with Carla continued into her seventies and we still continued to be good friend right up to the start of the virus and sadly we lost Carla fairly quickly to it. Now in my sixties I have a dilemma. Carla left a note for each of her children that in case she didn't make it she had things she wanted to tell each of her children and there was one for me. Mine told me that she had told Sarah that the man she called her father wasn't her biological father, but regardless of that she was always loved. It went on to say that she had used my DNA, cum. and proved that Sarah was definitely mine. It suggested that perhaps I should now own up and tell Bobby and Sarah the truth. The biggest problem is that in my late twenties I married Paula and have three children by her. I had managed to carry on an affair all those years with Carla and nobody knew or suspected us. They all just thought we were good friends because of bobby. I would like to know what SH readers think I should do. Keep quiet or come clean and tell everyone including my wife and kids that I cheated on them and that they have a half sister? Bearing in mind it could hurt two families.