My coworker did something wrong then blamed me

My coworker was called into the office over a mistake in in the office. Instead of just owning up to it, she stated that I actually mixed up theses sensitive documents on purpose to get her in trouble, really. I don't do this job, what the hell. So this person does something wrong then when she had to answer for this mistake her defense is I sneakily did this so she can get fired. What kind of person does this make me look like, not a real good one. I am horrified that this even came out of this person's mouth, I'm still shocked. So now what does my boss actually think of me. I think this is the ultimate blame game and defamation. Mind you this is not the first time this employee has made this exact mistake, however it's the first time I know of that she decided to try to make others think I am sneaky and manipulative and would actually do something like this. Basically she was trying to insert doubt, can't %100 say it was her, it could of happened. This is really bothering me, because not only did she outright lie, she now is hostile, like playing the roll, as if this really happened. So now I just don't think she is a liar, manipulative, she has cross into the zone. When you lie then go back to an office and play it off as if it is true for all to see you have crossed over to that zone. I have worked with the other coworkers a little over 18 years and all know she it outright lying. But one of the biggest problems is my employer is ignoring how she is acting, they don't know what to do with her. I'm ready to get a restraining order on this person, it's kind of scary someone would go to such great lengths.