This is exactly why you should never try to be friends with coworkers. Now there’s a good chance your coworker might hold a grudge against you (even though she is the one out of line). If something weird happens at work or a rumor starts going around about you, you’ll know exactly who to blame. If promotions come around, now there may be grounds to favor your “poor coworker” over you based on false claims. In the future you really should try to keep a hard boundary