Mother in Law

I'm Alan 41 widower and have 3 grown children, who have moved away. I married at 17 and my wife Ellen was 16 at the time of the wedding. Ellen died 3 years ago of a stroke, her mother Betty 55 moved in to help out. Her husband Frank had passed away 8 months earlier from Cancer. She had also married young at around 15 and pregnant, the usual thing in these parts. After my last child left home early last year, it was just me and Betty. She kept the house and I ran my business. We got along great, I wasn't looking for another wife and kept busy with my business. Sometimes I get horny and would masturbate and didn't think about other woman. Betty is in a local women's club and would go to meeting and things. One Saturday afternoon she was gone to a meeting or something they had on and I was home alone. Feeling a bit horny , I sat in the lounge and started to watch a movie. It wasn't a porn movie, but it was a sexy movie. I started to masturbate while watching it. I was lost in my own world and didn't hear Betty's car pull up or the front open. I heard a "Oh my" and turn my head to see Betty standing there. I quickly covered myself and said Sorry. She said No need to apologise, it's only natural and then she went into the kitchen. From there she asked If I wanted a coffee or something. Having put my cock back in my pants, I said Okay and went into the kitchen also. I saw her shaking a little and repeated that I was sorry for what she had seen. She replied That she wasn't worried about that and that she also got horny sometimes. She went on to say that she would play with herself at night and she missed her sex life with Frank. I then said Maybe we could help each other out sometime, expecting a big loud No. But she only said Maybe, later on I was sitting in the spa in my swimming trunks and Betty asked If I would I mind if she joined me. I answer No your always welcome and she took off her robe and got in. Ellen and me use to use the spa naked, as it couldn't overseen by anyone. After a bit she moved closer to me and reached out and took hold of my cock thru my trunks. I was shocked at first, but didn't say anything. Then she told me to remove my trunks and she would finish what I had started earlier. So I did and she started to stroke my cock and I was enjoying it. Then she stopped and said How about you and I go to your bed and finish this there. Okay I replied and we went off to my bedroom. She dried me and I her, then she removed her swimsuit and we got on the bed together. She went back to stroking my cock and I started to play with her breasts. Then I laid her on her back and mounted her, after I had finished we laid together for a time. Then she said Anytime your randy just tell me and maybe we do this again. I replied Ditto, after dinner that evening I asked her to spend the night with me and she agreed. We've sleep together ever since.