Dude, come on!!! It was one thing when you were just trying to be a nice guy for the sake of being a nice guy, but now she is pretty much telling you that the problem is YOURS, not hers. On principle, the principle being personal responsibility, you cannot give her a dime. Are you seriously kidding me? Take YOU to court? Over what?
This reminds me of the current season of the Bachelorette. Some guy named Brantley or Bradley, only came on to the show to promote his business, whatever that is. One of her friends called her and warned her about this guy, that he was only there to promote his business, so she had reason to doubt his authenticity. She still believed him. He decides he cannot take it anymore as he is actually repulsed by the current bachelorette, so he makes up a story that he misses his daughter too much and needs to get back home to her. She is crazy about this guy and is devastated. While filming him in those testimonial booths or whatever, he is making fun of her, saying she is ugly, has no personality, and that the only thing she would be good for is a quick lay. I mean this guy is on the same level as the guy in CA who killed his pregnant wife, Scott Petersen, that is how bad this guy is. She has no idea how he really feels and the show hasn't told her, at least not yet. She looks like a complete fool as she whines on and on about how great he is, how she really cares about him, all the while he is laughing at her.
In this instance you are the Bachelorette and the woman who bought the car is this Brantley guy. You are here on this site, the majority of us telling you that an "as is" sale is "as is" whether stated in writing or not. You owe her nothing, period. Meanwhile you seem to be riddled with guilt over this for no reason. Now, she makes it clear you are the enemy, that she will take you to court if necessary. You still are not certain what to do here? Come on, it is time to "go to the mattresses!"