First off, welcome to PC! It's likely that your friend went through some kind of trauma and simply wanted to get away. It sucks to go through what your going through, but at the same time, I find it easy to sympathize with both you and your friend and here is why:

I'm considering doing something similar soon when I save up some more money. Most of my family are heartless people who don't care and I'm desperate to start a new life and be free from trauma incurred from an abusive past finally, so I'm strongly considering kicking all but my closest friends out my my life, changing my name, phone number, email addresses, and leaving the state.