Mother's best friend

My mother's best friend, Erika, suddenly came to the house. He apparently ran out of a fight with his husband... That afternoon, I heard Erika masturbating in the toilet. I was excited by Erika's nasty voice, and although I knew she was my mother's best friend, I began to become aware of her as a woman. And then I couldn't hold back any of my uneasy feelings, so I went to Erika...