You posted some important info here that we could all learn from. Marylin was abused by her family member. This is someone she knew intimately for years, where she could not have "misunderstood" her to be abusive. We are not dealing with a brief one-time encounter with a stranger, of whom we sometimes misinterpret the look or the tone of voice.

Having a mental illness does not invalidate the abuse. If anything, it increases the likelihood of a person being targeted by an abuser who preys on her vulnerability. The abuser finds her to be an easy target, as she could use her condition to invalidate her story and silence her. The absuer places so much distress on someone who is already traumatized, so that she appears all the more unstable and incoherent when she speaks (I'm talking about myself as I was diagnosed with anxiety) and feels less confident about her story being believed, especially against her abuser who is a smooth-talker and a great actor/ actress. The abuser finds it easier to completely break someone down who is already halfway there from childhood/ past trauma.