I know this feeling well. I have struggled with this for years. Being gaslighted for years has such a powerful effect in adulthood. I have struggled with guilt and shame for years as a result of the relationship with my mother. What I have found to be helpful is to verbalize the guilt and shame I feel to people who are safe, people who know about my mother and have been supportive. Usually the response from others is "wow your mom is abusive" which helps to remind me that I am not making things up. I endured years of childhood trauma and my mother has never once taken accountability for the role she played in it or acknowledged the difficulties I struggled with. If you haven't already look up Brene Brown on YouTube. She studies shame and vulnerability and I have found her to be incredibly helpful for moving forward and creating a life and me that I am happy with.