Recently Married

I'm Cheryl 22 and married Gary 25 in late 2018 and we live with my divorced mother Dianne 41. I was already 4 months pregnant at the time of the wedding. It wasn't the reason for the marriage, we had been engaged for a year at the time of the wedding. The main reason we lived with Dianne was she had a 4 bedroom house and it was closest to our workplaces, then we could get by renting our own place. Also, Dianne offered and at first, we hardly saw her. Several months later I stop work for the coming arrival of our son John. Then after the birth to look after him, when I returned to work 6 months after his birth. Dianne would be home to look after John while worked as she worked night shifts. Gary work shift work and sometimes I wouldn't see him for weeks or if I did he was sleeping and was gone when I woke up. Then in January, my workplace was shut down due to a fire in the electrical panel and the power was turned off. I returned home and caught Gary fucking Dianne in the lounge room. I was shocked and angry at the same, but Dianne said it was better to have him fucking her than someone else and I knew that Gary liked sex and wasn't getting much from me because of our work. Dianne also claimed to have seduced Gary, I knew it wouldn't have taken much trying on her part as Gary gets horny very quickly. Then Dianne suggested we have a threesome and she came over to me and started to fondle me and soon Gary joined in fondling me. So I joined in and we had sex together, since then we all sleep together in Dianne's bed and when Gary's at work Dianne and me make out. Recently Dianne missed her period and those not yet confirmed we think she is pregnant to Gary.