Unknown to our respective spouses, my sister is having my baby that is due in 5 months. We are sexually attracted to each other and have sex on regular basis for last 21 yrs. I am 38 and she is 36. We're addicted to each other and leading our respective married lives successfully and even have kids from them. Her husband thinks the child is his but in reality, it is mine. This is first time I am sharing this and I feel happy and light now.