Don't know how to explain to my family that they're being racist?

Since I was around 13-14 (now almost 20), I've been noticing that my (white) family members often make racist jokes. I've been calling them out on them and we have debates a few times a week because they say their comments are not racist and I say they are. Here are the recurring ones:
My dad did blackface to dress a character of a movie for Halloween (can't remember who) a few decades ago and still now brags about how great his costume was. I don't know how to tell him that he did not need to paint his face black and could have just used other characteristics the character has, but he argues that it didn't do any harm. Also always makes racist jokes and says they're just jokes so it's alright. I explained that the jokes are not funny because they only consolidate negative stereotypes etc. He also does not see the harm in saying the n-word and says it just to annoy me.
My grandmother says racist things as well stereotyping POC and if i point out that what she is saying is racist she'll get angry and say it's just the truth.
Every-time I call them out on their racist comments they say i'm just a 'feminist' (don't see what this has to do with it) and too sensitive. I don't know how to make them understand that comments like these are not acceptable to make. My dad does not treat POC differently and does not mean what he says but he just doesn't understand that racist jokes are just not funny. My grandmother, on the other hand, is racist and does treat POC differently (grabs her bag when she sees a Black person walk by etc). Any ideas on how to explain to my dad that racist jokes are harmful, and how to explain that the n-word is not a joke and not funny to say? I've tried reading about this in order to explain it to them but it doesn't seem to work. Especially now, I want them to understand that theyre being racist even if it is not intentional, but I just don't know how to word it for them to understand.
(sorry if there are mistakes, English isn't my first language
Don't know how to explain to my family that they're being racist?
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