I am a recovering heroine addict. ?

The last time I shot up, I decided I have had enough. My life had become unmanagable after several attempts to get clean. The worst part is I'm only 20, and what hurts me and makes me feel guilty is I'm a soldier in the army and I have family who call me a hero. I deploy to Afghanistan in 2 months and I assure you, I'm no hero. I look down on myself and know I'm a failure; I failed myself, my family, my battalion, and my creator. I feel I have no purpose and I have wasted so many great opportunities.... Well fed up with my life tired of letting people down, thinking about my mom and dad saying they are proud, picturing their loving, supporting, so incredibly proud faces(which for the first time, they were proud and I could see it as tears rolled from their eyes as I marched across the field graduation day from basic training). These were theimages and thoughts that finally tore my heart as I felt like a fake, pretend hero, the most in-honorable soldier and son, I decided to shoot up 3 times the amount I have ever done. Instantly I knew I had od'd as I closed my eyes and waited to fall into hell where I had accepted I belonged too. When I passes out, all of the sudden I noticed I was awake but I looked down and saw my body convulse on the floor foaming at the mouth and gurgling bleading out my nose. I thought it was a dream as I watched myself stop breathing and my eyes roll back. I stared at myself for 3 hours and woke up to blood from my nose everywhere and foamy saliva all over my face in the same spot/position/same carpet wrinkled up the same way. I don't know but I believe I died for a few minutes. Why did I get a second chance? Do I deserve it? I just want to know I'm not a waste. I've been clean for 77 days now yet I still feel like a failure because all I think of is my parents finally satisfied so proud with tears in their eyes face not knowing I was a junkie. They know now, but I just need some help, advice, am I worthy of "hero"?