I made a racist joke- where to go from here / next steps?

I (19m white) had a friend (19m) from online. He knew where I lived but for some reason he’d never tell me where he lived- not even a general location. Eventually he said he lived in Korea- then switched it to Europe- then Korea again. It became kind of a joke between us because it was so absurd that he changed his location regularly. We were in a group chat with 3 other friends of ours.. I’ll call them E, J, and L.

My friend eventually called me a stupid American during our banter and called me “racist” and I in turn called him a “stupid Korean European” as a joke- now I was fully aware he didn’t live in either places, but I said it anyway. Eventually “L” asked why we were being racist and in response my friend said “he’s only racist to me” and I replied with “that’s right European”. Eventually in a later conversation I call him a slow ass European Korean.

A week later I see “J” post a story talking about how racist jokes aren’t funny- which I agreed with and liked- but then I didn’t realize he was talking about me specifically. I (and my friend) were falsely under the assumption that what we did wasn’t racist because we weren’t originally intending it to be about race- but about the places we were or weren’t from. But I apologized to everyone because I did offend and make people uncomfortable. Although even today I am scared to be around POC- not because of them but because I don’t want to make others uncomfortable due to my racist past- because yeah the joke was racist when I look back on it despite intention.

I’m trying to be a better person, so I’ve been trying to listen to the people who are affected by it. What kind of things should I be doing / not doing moving forward? I won’t make these jokes again obviously- but I would definitely like more guidance (if you want to of course).