There's not really much information but this could be a temporary mood...that your friend tried to vent. Sounds like your everyday fight. Just talk to her tomorrow or a few days after why she did that, when she's calmed down. If she was a good friend, she'd apologize. If she doesn't then...try to give it more time? If it doesn't work for you, just drop her. Or like everybody else said ^...she might be worried about your health.