My brother's Mother in law

I'm Karl 22 single, I'm the only family member who lives close to Barbara 48 divorced and my brother David's wife Sara mother. They both live in the city and were unable to help Barbara much after her car accident early last year. I had moved to Barbara's town for work the year before. After Barbara was released from hospital, Sara took care of her till she could take care of herself. But she couldn't mow her yard or take care of her garden and I was asked by David to take care of yardwork for Barbara. I agreed and would go by on the weekend doing whatever yardwork that needed doing. Barbara and me got on really well and after she recovered, I still went by and helped her. She had a problem with her back stairs and I fixed it for her. I was there on a Friday night for dinner and a bad thunder storm started and the power went out. There was a lot of lightning flashing across the sky and Barbara suggested I stay the night. I accepted and I went to a spare to sleep. About an hour or so later there was clap of thunder right over head and the whole shook. It woke me up and I heard Barbara scream, so I went to see if she was alright. She was shaken by the thunder and with the power still out we could barely see anything. Then another flash of lightning lit her room and she saw my cock was hanging out of my shorts. Without saying anything she took hold of it and started to stroke it, I was a bit shocked at first. But let her carry on stroking it. It soon harden up and she then went down on me. I blew my cum into her mouth and she swallowed it, she asked me to join her in her bed and I did and I fucked her twice before we went back to sleep. In the morning we fucked again and with the power still out check for damage around her property and then went to my home to see if there was any damage there. No damage at either place, my place had power, so Barbara made us breakfast. Then with nothing else to do, we fucked in my bed and returned to her home and fucked again. Just before noon the power came back on and we showered together and went back to her bed and fucked again. Since then we have been fucking most times we meet. It just sex Barbara said and she told me to find a girlfriend. I have started seeing Anne 20 and we have recently started fucking and I'm still fucking Barbara. Anne knows I help Barbara with her garden and has met Barbara, but doesn't know I'm fucking Barbara.