At daughter's request

My daughter Helen had her second child and had trouble having sex with David her husband. Post natal depression her doctor called it, she felt bad as he was a good husband. So she asked me her mother to provide sex to David, I'm Barbara 49 divorced and live across the street from them. I was shocked her request at first, but not having any sex life myself. Except for playing with myself, I asked what does David think about your idea. I haven't asked him yet, I wanted your agreement first. I said okay if he agrees and so that evening David was watching T V and Helen and me went to see him about her idea. As usual when she said she wanted to talk to him he turned off the T V. She laid out her idea and he was shocked and with Helen adding that until she got over the post natal depression he wouldn't get much sex unless he accepted her proposal. He looked at me and I said I'm okay with it if you are. He just said he would think on it and let us know. An hour later I was about to head home and he said he had a question and Helen said what is it. If I agree how do we go about it he asked, Helen said mom stays the night with us in our bed and you fuck her. Then adding that way we are all involved. With that he said okay count me in, so I stayed the night and got fucked. In the morning David asked how often are you willing and I said just ask and I will or won't let you. As it turned out I was very willing, so much so that I moved in with them and sold my house. Helen got over her problem and we still all slept together and Helen got pregnant again and is due in June. Whether she get post natal depression again doesn't matter as I'm still letting David fuck whenever he wants.