The analogy is spot on.
The n-word is a slur. It is a term used to insult and demean, rather than just describe.
So is terf.
As for feminism... Honestly, I'm not sure if you lack the capacity to understand or are so convinced of your virtue that you can't get your head around another POV, but feminism is about women. That is, the old fashioned XX type. The type repressed and abused for millennia because (get this) they are the ones who have the babies which puts them at a massive physical disadvantage.
Women, due to their biology, were shat on from a great height for centuries. Men wanted to control reproduction, so they needed to control women. They were, on average, significantly bigger and stronger (this is because of a hormone called testosterone, which you may have heard of), so they were well able to control the baby-makers, and in many places they still do. Women got a bit sick of not being able to own proper, or vote, or earn the same as men for the same work, hence feminism. Hence the rejection of gender roles and stereotypes, which just serves to keep us in our (very unequal) place.
Feminism, the sort I ascribe to, is about women, not people who were once men. It's about the rejection of gender, while at the same time acknowledging that there are real differences between men and women. Trans rights are not the same as feminism. I can believe that feminism is about actual, natal women, and still be 100% in favour of trans people having the same rights that we all have, provided (and this is the kicker) that doesn't result in women being, yet again, shat on from a great height, and losing oh, dunno, the right to be safe if incarcerated, or to compete fairly in sports.
I hope that's clear.