My mother's friend

Long story brief version, I was away for several years and returned home and decided to stay with widowed mother Jennifer 48. She lived in an apartment building on the fourth floor and worked in a dentist office as receptionist. She owns the apartment and it has 2 bedrooms and so I could stay as long as I wanted. I'm Mathew 29 single and worked in construction while away on my return I got a job as night security at large office building. So I worked nights and my mother worked days, a week after starting my new job It was a Saturday afternoon and Kristine 53 a friend of my mother dropped by to see her, they worked in the same building and had almost lunch daily. Kristine is similar in size and looks of my mother at 5'6' or so fuller figure okay looking for their age great tits. Kristine is divorced and her children had left the nest for their own places, Kristine had just purchased an apartment on the sixth floor in the same building as Jennifer and was moving in that day. Also she had taken another job with the same company and would be working mixture of day or night shifts. Supervising mostly, but it came with a pay rise. That was the first time I met Kristine and I noticed she kept looking at me. Over the following weeks I saw her a fair bit more, usually just as I was going to work and her dropping by to see Jennifer. Then on a Tuesday Jennifer was at work and I just awoken from sleeping after a shift there was a knock on our door. I opened the door and Kristine was there, I was surprised to see her as Jennifer wasn't home. But she hadn't come to see Jennifer, but she had came to see me. She quickly got to the point. She wanted to know if I would like to have some fun as she put it, meaning sex. I was a little shocked by her request for sex, but I don't get muck at all. Especially working nights and my cock decided it was great idea and went hard. So Kristine joined me in my bed and I fucked her twice, she left just before Jennifer was due home. I showered and I was having my dinner when Jennifer got home, we talked awhile then I went to work. Every time Kristine worked nights she would come over to be fucked and I was really enjoying her visits. Kristine took some leave to visit a new grandchild and I was left waiting for her to return and found myself checking out my mother. On Kristine's return sex resumed and still is a regular release for us both.