Sorry to hear about this but you're right 100%. I had a similar story with my best friend (back then she was). She had an opportunity to go to Mallorca, it was a last minute deal but she had no money to spend. I lent her some and she promised me she won't spend it unless it's necessary and she would give me back asap.
She spent all the money on clothes. She was living her normal life, bought all she needed for herself, bought stuff on credit and every time she told me she can't give me my money back as she didn't have any. Took me two years to get my money back and it wasn't a huge amount.
With friends like these who needs enemy, right? I've learned my lesson just like you. Never ever!