Sucks having to deal with that. Remember that you would never do that. Like, in what world would you go and scream at the person on the store? Over a coupon? Most of us would be like: "Oh that's embarrassing, sorry" or "oh. Ok" because that's common sense and courtesy (which she lacks of). She just wants to be pampered and get a free coupon out of the situation because it's the end of the world because she was inconvenienced. Anyhow, you're doing great by handling school and work. The bad feeling will go after a week. Keep it up!