Being called a racist is very hurtful. Imo, you can only determine whether someone is a racist by observing their actions, i.e. intentionally demeaning someone because of their race and that alone. Racism is serious business.
It would be to me like someone calling me lazy, or I didn't "work" because I'm an artist, work at home and choose my own hours. I freelance.
Back to the subject. I had a boss one time, Bill Knapp, who was a tail gunner in a B-24 during World War II. He was about 60 years old when I worked in the appliance dept. at a wholesale electronics and appliance store (my first Summer job.) He was a character, let me tell you. He showed me a picture of him and his bomber crew, and I wish I had that picture today...man. He was a reformed alcoholic, and didn't take a drink at all. I remember one time he brought in a little weed to load in with his pipe tobacco, and smoked it sitting at his desk in the office. So this was a cool guy for an old man.
He told a lot of stories about his experiences...didn't talk about the war at all, but my Dad told me he was shot down twice during the Ploesti oil field raids.
Anyway, one time he was very upset in the office. Evidently someone had called him a racist...don't know who, (had happened earlier at some time, and don't know when.) But he was po'd and resented it extremely.
He was not a racist. And I don't think you are either Rip. I don't blame you for being upset and thinking about it. People don't think about what they say, and are thoughtless jerks.
If it was me, I think I would have said something to the boss about it, if I thought t would interfere with my job performance, and if I felt the co-worker was trying to be malicious. Probably not the case, but sounds like things may never be the same, possible loss of a friend.
Sorry this happened to you. Lesson learned the hard way. I'd tend to avoid this person, because she seems confrontational.
Les