I have this issue also. I am fortunate to have siblings that watched the things my mother (the abuser) put me through. I think the majority of blaming myself actually comes from the gaslighting behaviors of my mother. At least that's what I've traced it back to. Her constantly telling me that I deserve to be treated a certain way because of x, y and Z. That she is just being a good parent. Her bragging to her friends about abusing me as if it is not only acceptable but expected. It isn't easy to overcome this psychological manipulation.
Like I said I have siblings that watched this happen. They tell me that she was wrong. They tell me that I didn't deserve it and that they weren't treated this way. They tell me that they would never do those things to their children and so on. It is also a healthy reminder when I was hoping my friends and siblings with their children that good parents aren't abusive. I have also noticed with age how my friends parents are with them and it illustrates how abusive my mother really was. This helps when I am feeling to blame and my siblings aren't readily available to talk to. When in doubt I look to those people in my life that have healthy familial relationships to draw examples of how I'm not crazy or wrong, that I didn't deserve what I was given.
I also recently had a justifying moment when my baby brother told me that he had to watch my mother break down on multiple occasions when she was drunk about all of the horrible things that she did to me. I just found out last week so this will be my new source of strength but the other methods have helped for the past 21 years.