Many people make wrong decisions on life. Is it because of depression? because we're hurt? well, it is because we do not know how to accept things and learn from our experiences.
I've been through to that situation called "Depression" and it's not easy to handle it. you can't easily trust somebody with your problems, there are times you're afraid to feel happiness with in you cause you might feel devastated afterwards. I once became a spoiled person, I want the people around me to be with me as always, i want to have the things i want, I want to go everywhere (take road trips, get drunk, and get wasted) and lastly I want to end up my life. I took a deep breath and think about life, then suddenly i just realized that these things happen cause we're obsessed to have those things which we think could make us happy but to be honest it is useless. Life is just helping us to have those people and things which is more deserving to have those.
Try to think the positive sides, I can assure you that it would really help you get through it. If you have a friend who's into such situation help them, try to understand them, and explain what life really is and show to them that they are blessed to have you in their life. through thick and thin don't you dare leave your friend just because you've found a new one or you're tired of having him.