AIO? My parents! age gap gives me the ick

my (30F) parents have been divorced for 30 years (My dad cheated and left her).

i am very close to my mum (65F) but have been NC with my dad since my first kid (6F) was born. (context: My dad is mentally unwell (think CPS) and neglected, sexually and physically abused me. his next partner psychologically abused me from when I was young. i’m in intensive therapy to try and deal with my ongoing C-PTSD).

ANYWAY, something that increasingly gives me the ick is the age gap between my mum and dad. They met at a club when he was 17 and my mum was 28. he’s 6’4” and she says he lied about his age, and by the time he finally told her, she was in love with him. He’d already left his abusive home at the point, so no parents to put a stop to things.

they got married when he was 20, she was 31.
I was born when he was 24, she was 35.

the thing is, when I was 17/ in my 20s, I never thought much about the age gap because I thought I was a completely mature adult.

What‘s really tipped me over is that I‘ve started teaching kids at uni who are 19/20 and THEY ARE ACTUAL KIDS. I worry about them being safe, and being cold when they get soaked coming to class in the rain. the idea of someone my age getting into anything with someone their age is revolting.

i adore my mum, but farrrrkkkkkk she always brushes it off when i ask her what the hell she was thinking because ewwwww. She was also a teacher (young kids) and I feel like she should have known better? I also feel like her friends all normalised it at the time. The two I’ve spoken to recently also brushed off how weird it was.

I can’t let it go. AIO?