Five months of newlyweds, I impregnated my wife's younger sister before my wife...

I think I'll have a child soon... My life has stabilized, and one day, when my wife and I worked hard on having children every night, my wife's younger sister, Fumino, was staying at our house for five days. They continued their relationship with the couple, thinking that if they were careful, but it seemed like they had been leaking out, and Fumino couldn't sleep. Then we became aware of each other and we began to have a relationship without our wife knowing. The number of times gradually increased, and all the sperm used to make a baby with his wife was used for her sister, Fumino.