My Gran likes to stroke and suck my cock

I'm Norman 26 and live with my grandma Rita 68 widow and my mother Ruth 45 divorced, I work shift work at a warehouse center. Ruth works at a lawyers office and is gone most of the weekdays. It all started in late April I was home and Rita had been diagnosed with early onset dementia in February and we done everything to make her happy. The doctor told not to distress her and let her do what she wanted as much as possible. So I was off duty for a couple of days and just laying on my bed in my shorts and Ruth was at work. When Rita came in and I thought she was looking for my washing or something. But instead she came over to me and just stood looking at me for a time, I asked what's wrong. Oh nothing was her reply and shortly after she put her hand inside the fly of my shorts and started to play with my cock. I was shocked and was about to asked what she was doing that for, but remembered not to distress her. So I stayed quiet and let her continue and she started stroking my cock which went hard. She kept stroking it and then she bent over and started to suck my cock. I stayed quiet and started to enjoy her sucking my cock and only spoke to her to tell her I was about to cum. She kept sucking and I came in her mouth and swallowed it all. That finished her interest in my cock and she left the room, only saying as she left that was nice. Later in the day I was in the kitchen and Rita was looking thru a book. When she stop and came over to me and wanted me to drop my pants. I thought she might want another go at my cock and it went hard straight away. Again she took my sperm in her mouth and swallowed the lot. Later on when Ruth was home, I told her what Rita had started doing. She was shocked at first, but told not to distress Rita. I went to my room and was laying on my bed and again Rita came and started the same thing. This time Ruth was home watched the whole thing with Rita sucking my cock. After Rita was finished she went to her bedroom and stayed there until morning. Ruth was as shocked as I was and just told me again to get on with it. So I was told to let do what she wanted as long as I wasn't hurt in anyway. After several weeks of Rita's head jobs, I started getting hard-on every time she was close by. At the end of may Ruth was certain it was caused by the dementia. But didn't ask the doctor about it because it was a sexual acts with her grandson. So I just let her do what she wanted. Then one night I was in my bed about to go to sleep, when Ruth came and joined me in my bed. I first thought she was there in case Rita may a visit, well she didn't. Ruth was the one that got horny and she started play with cock and then going down on me. We ended up fucking and it became so regular for us that I always totally ready for sex with Ruth any day or night. By the end of July I decided I should try to fuck Rita and the next time she started to suck me I started to play with her. Nothing besides some fingering happened, but as the blowjobs come and when from Rita the more I got away with her. Finally fucking Rita early September, Ruth and me now sleep together every night and are joined by Rita about once or twice a week. I only fuck Rita when Ruth is at worked. I don't have siblings or cousins. But fucking your mother and grandma is great and Rita is happy. So is Ruth and me.