Repressed (?) memory from years ago

TW// physical abuse

I only remembered this event very recently when I was trying to sleep . I'm not in a good headspace as it is.

She slapped me when we were both drinking. Clearly to her it was a joke, it wasn't hard at all, just a nasty shock, and she was giggling and grinning. I looked horrified and surprised, it's obvious she thought there was nothing wrong with it. Who am I kidding, she gets a real kick out of doing what a mother isn't supposed to and laughs at my reactions.

I'm not proud at all of what comes next, I slapped her back BC I thought she would understand it was wrong. Because when she does something wrong it's supposed to be fine according to her, but when I do, suddenly she treats me like a criminal. But she just slapped me back.

Did not go any further, but I only just remembered that memory yesterday and it is chilling. I think that must have been a repressed memory, or just something that's drifted from my mind because I tried so hard at that time to ignore it.