I seduced my son

Long story short, my husband John was badly injured and had brain damage as a result, I became his full-time carer. We had 2 children Shirly 22 at university and Alexander 20 carpenter lives at home. Alex, as he is called, is a quiet person as a whole and doesn't date and keeps to himself. I'm Joanne 44 and we're fairly well off financially, due to family and insurance reasons. We live in the city as John needs to be close to specialized medical care, Shirly lives at the university across the city from us. I don't get out much myself but if I'm able to get out it's not for very long. John, for the most part, isn't a problem as he is very quiet most of the time and doesn't speak at all. But last November I started having sexual dreams and was feeling horny almost all the time. We have an enclosed heated pool at the back of the house and Alex was swimming and I became aroused just watching him swim. But I was able to satisfy myself and again later, but it became harder to do as time passed. Then in December, I was finding a lot harder to satisfy myself and really started looking at Alex in a sexual way. I tried getting John's cock hard so I could fuck him, but had no success. Then I saw Alex masturbating in the garage one day and that was almost too much for me. But I had visitors at the time and by the time they had left Alex had gone out, I tried to satisfy myself and couldn't. On his returned I asked him to rub my feet, he does this for me at times. So as he rubbed my feet I allowed my dress to rise up so he could see my panties if I had been wearing any and I watched for any reaction from him. It took a little while before he noticed my vagina. But after he did, he kept looking at it and trying to hide that he was looking at it. Then I pretended to get a cramp and spread one leg out and away straightening it and giving Alex a better look at my pussy. It worked as he got a hard-on and I wondered how I could get him to ask to or do something sexual with me. But my cellphone rang and this distracted him, it was Shirly saying she wasn't coming over till Saturday. I had forgotten that Shirly was supposed to coming over that day. With that out of the way, I turned my attention back to Alex. I decided to push my luck so to speak and asked him to rub my inner thigh to ease away the cramping I said. He started to rub my thigh and I told to go a little higher, hoping he might start something. But he didn't, he did touch my pussy a couple of times and I think he wanted to see what I would do. So I told him he was doing a great job. Hoping he would go further, but he didn't and I could see he was getting very uncomfortable with his hard-on. I decided to try something else and pretended to notice his hard-on and asked him if I had done that to him. He just nodded and then I said I should help him take care of it, he just looked at me and I told him to remove his trousers and after he did. I took hold of his cock and started to stroke it, shortly after I went down on him sucking him off and then I decided it was time and I mounted him. He didn't take long to blew his load inside me and after he had I said we should shower together and I was able to get him up again and got him to fuck me. Since then I have been fucking every week and then last week when John was put into the hospital for a couple of nights. I came home and caught Alex fucking Shirly, Shirly had come over and caught Alex masturbating and it went from there. That was our first family threesome and with Shirly moving back home this weekend, it won't be the last.