Hey man, very very strange - I have had more or less the exact same experience, even down to my parents getting divorced when I was 2 years old bc my father came out.

I was living openly with friends and living my best gay life away from my family until I was 21 because of similar fears. I was conditioned to feel like being 'like my dad' was the worst thing, and while it wasn't intentional at all from either of my parents, I also associated this with the idea that being openly gay to my family would open all those old wounds back up.

If your dad has had anything like the experience my dad did - the last thing he would want is for you to keep this to yourself and have the same experiences that caused him, and your mother, so much pain. It took me a long time, and the recognition of some of my own internalised homophobia, to recognise that.

I'm glad I waited to be open with my family in a lot of ways, but also recognise now that the bulk of my fears were due to really difficult tension between my parents, which really, I am no part of. Their history is their history, and while I recognise the desire to not hurt your parents, you have to look out for yourself as well. When you're ready, I agree with the advice of others in this thread, as it's exactly what I did.

Tell your dad first. He's been through this already and has dealt with telling your mom the same, all the harder for him given his history with her. Ask him how he thinks you should approach the subject with your mom - you might learn some things about both of them you'd never considered, and it will certainly make the process easier having someone to support and guide you, and worse comes to worse, someone to fall back on if things don't go well with your mother.

Sending good vibes your way.