Lindsay, I realize you don't know me and that you are probably being given advice from a lot of people. In fact, someone may have already said these same things to you already. Humor me and read what I have to say.
You are a talented, beautiful young lady. You are also strong, which is evidenced by just the little I know about you: you have been able to achieve success in a highly competitive industry all while you have dealt with some difficult family situations. Take pride in this. It is not easy.
You must stop looking for happiness outside of yourself. You will never find it. In fact, when you look for happiness outside of yourself, you will only find trouble, grief, and disappointment.
You have to start giving back to the best friend you have ever had: yourself. You are the one that has gotten through the tough spots in your life. You can do it again. In order to get past these recent mistakes you have made, you need to reach inside and ask yourself for the help to do it.
Be good to yourself. Be proud of your accomplishments. Learn from your mistakes. Be happy in who you are. If you need to change something, do it. For yourself. Be the friend you so desperately need.