how to get over the mother of my child?

It's been over 6 months since we broke up and i still love her.. I find myself in tears thinking about her.. She was my high school sweet heart and became pregnant when i turned 17. Everything was perfect between us. So i thought. Well i found out she was unfaithful in the beginning of our relationship and became depressed. Tried to look past it as she was only 14 when it happened and it was years ago. Well she cheated again and when confronted she became irate and became abusive. I made a series of poor descision because i was heart broken, and i slept with 2 of her friends. She had continuously cheated on me for a year before that. Well long story short i left her and she is with one of the guys she fooled around with.. It's been 6 months and i still miss her.. I started self harming, drinking heavily, and abusing xanax and ecstasy. I was going to parties and sleeping with random women hoping to fix my confidence. Nope. I had women show interest in ne but i just can't feel **** anymore. I feel depressed all the time. And recently started smoking a pack a day.. So anyways anyone go through anything similar and any advise?