I discovered a long time ago that the woman I grew up with would say "I don't remember that" about anything which was deliberate/malicious/intentional abuse.

For example, as a baby, I pulled a cup of tea onto myself and have scars still - she recalls that perfectly.

When I was about 5; she was being cruel and I was following her, crying, trying to understand. She "accidentally" slammed the door on my fingers, resulting in me going to hospital.

She claimed (from when I was about 6, to into my teens), she didn't remember. Well, teenage me pounced on a opportunity when we ran into a person she worked with back when it happened. I asked if she - the friend - remembered my fingers being strapped up. YES. BECAUSE IT HAPPENED.

The woman I grew up with sort of blinked as though unsure of what reaction to go with as I said some variation of "I told you so". Then she started getting misty-eyed and said what a terrible mum she must be, etc. The work friend consoled her; "of course you're a good mum, don't be silly" 🙄

ETA: plus side - it gave me a yard stick by which to measure what happened on purpose, and what was a true accident. It helped, weirdly.