Bangin my girlfriend's Step-Mom

My girlfriend's Step-Mom dropped by unannounced, when my gf wasn't home. She started asking me really inappropriate questions, like have I had sex with her step-daughter yet? She said her husband doesnt satisfy her sexually, and that she wanted to make sure her step-daughter would be satisfied sexually before the two of us got married. She insisted that I fuck her so that she knows her step-daughter would be taken care of sexually. I tried to resist, but she was not going to take no for answer.