Has this ever happened to you?

Now this is pretty much the worst experience I had to go through all year. Here's what happened: This person that I know and WAS (said for a reason) cool with at the time was in a bind, supposedly. She needed wheels since her car was repossessed, and needed wheels. A co-worker of ours was supposedly selling a car, and she wanted it, but here's where it got bad: She wanted me to help her out. It wasn't just a few extra dollars. She needed a large sum, like in the hundreds, make that 600. I wanted no part of this and was trying to get out of doing it. Everything I can, like moving away from the subject and was told to stick by my instincts, and I was trying to. Then came a certain point when she was hounding me for the money. Of course, in the end, it was 400 dollars less then what I had given to her, so it was only 200 dollars that I gave her, not 600, but in all honesty, I wanted no part of this. I had deliberately told her that I despised lending people money because I had been screwed over before. I didn't want it to happen again. Even when she was hounding me for the money, I was getting sick to my stomach. Very queasy and nauseous. The only reason why I gave her money was because I had enough of her hounding me, in other words, she cracked me. I never saw her again after that day, but I have a feeling that I will see her or speak to her again, but it won't be in the most pleasant sense. I am really pissed off at her because of it. In all seriousness, you can very well think that I was too trusting, but that wasn't the case at all. I learned that I need to put my foot down when I seriously don't want to do it, especially if it's something that I really hate doing. Also, it was hard to say no, even when I tried, because I was fed a bunch of crap like "I will pay you back", "I'm not trying to screw you", etc. Since then, I have not had any reason to speak to her. If she ever does call, or if I ever cross paths with her, she better be in for the biggest confrontation of all.

Also, have you ever gotten queasy when you were under a lot of pressure or stress? I heard that it can happen under extreme circumstances that extreme stress can lead to you wanting to throw up.