How do i stop being bulimic?

It all started 4 years ago. I was a very happy chubby 18 year old girl. The guy i was dating for about a year broke up with me so i became depressed. It was never my intention to lose weight but my appetite was gone for several weeks. At that time i remember being sad all i didi was cry and sleep so i lost 30lbs. One day i woke up thinking it was time to move on but i also realized how thin ive gotten so thats when i became some days bulimic some days anorexic and lost another 30 lbs. four years later i look like i wanted to bodywise but i feel unhappy with bulimia. Ive tried to stop but it keeps coming back. I am a 23 year old living a great life why is this taking over me emotionally and mentally?