My wife's sister

I'm Peter 32 married 3 children good career, last year my wife's Annette's sister Kerry-Anne came to live with us after her divorce. Annette older sister by 2 years and only sibling. No children of her own and really down hearted after the divorce, always putting herself down was also depressing for us. I told Annette we should hook Kerry-Anne up with some guy and get her laid to cheer her up. Annette didn't think it was a good idea and said she might hurt again, but agreed she needed fucking. Then she shocked me by saying I should fuck Kerry-Anne and that way she wouldn't be left depressed. Still a little shocked I asked how would she not be depressed if I was able sleep with her, she would then feel guilty that she betrayed you. No she won't, because we will make it a threesome and she won't be betraying me. Still unsure I nodded my agreement and left to Annette to arrange. Arrange she did and about a month (October) later we had our first threesome and now regularly sleep together today. Only problem that was missed was Kerry-Anne was on any protection and she has since got pregnant. A shock to me and a delight to both Annette and Kerry-Anne, mainly because the divorce was caused due to her not getting pregnant to her ex. She was very quick to inform him on her getting pregnant, but didn't tell him by whom she got pregnant. So I'm to be a father again and only close family know I'm the father and show their support. Annette and Kerry-Anne share my bed every night.