I don't want this associated with my main acct (gf to know about this) so I've made a throwaway.

When I used to live in Alabama, I worked at a pretty slummy family-fun type establishment with arcade games/laser tag, etc. Well I try to be as passive/respectful as possible with all my coworkers when I'm at work, and that's how I was at that job. There was a black girl named Shanay that was the only one to ever have a problem with me (still to this day don't know why). I would even go out of my way sometimes to show I wanted to be a friend of hers, by being contemplative or smiling, or w/e I did as I enjoy being on good terms with coworkers. The first time I knew something was wrong is when my other friend Terrel told me Shanay was talking behind my back in the break room saying something about me being like all other white people. When Terrel said this, I didn't really know how to feel or what to say. A few days passed (where I considered just not asking her about this, and I shouldn't have). Anyways I ended up asking her about this and if I ever did anything to offend her. She just replied with a really snappy 'no.. what is your problem!?' I said I didn't have a problem and that I just hoped we were okay and that if I ever offended her that I apologize. She pretty much just walked off and went back to work.
Anyways, a week or two pass and one day I'm brought into my managers office and told that there has been a report that I have made racist comments toward other coworkers and that I need to watch the things I say... I was completely blown away by this. So 2 months go by and I'm called into my managers office again, this time being told that Shanay specifically stated that she heard me call her the n-word under my breathe passing her one day..
I didn't know what to say or do. I had never made a racial comment period working that job, and they told me that I was a risk, showing un-professional behavior. I was let go at the end of that meeting. I thought about telling my manager that I'm positive Shanay for whatever reason didn't like me from day one, and that she was race-baiting to get me fired. My manager was black so I didn't think this would help my cause.
Anyways, it was a very emotional time for me and very upsetting. I hate to seem closeminded about this topic but nowadays, I have real worry that if this ever happened again, i would be fucked... again. It's like... if any non-white person I work with doesn't like me, all they have to do is makeup a racist situation and I'll just be fucked again.
I work at a primarily black call center now and this job really is much better, but here and there I definitely meet a person or two that comes off very passive/rude towards me and it freaks me out.
To say the least, I keep to myself at work. I try not to do or say anything that isn't directly relating to the job. I don't like being that way, but I can't afford something like this happening again.