Why cant I quit using drugs?

Addiction/Habbit.... I know. But, I really want to stop. I am a serious addict. I can barely leave the house without going to different buddies houses (who all have different drug preferences) and using. I am a ******* loser. I use for days straight and then crash, feel like ****, eventually feel better and use again!!! DAMNIT!! Last Wed. I stopped by my buddies house, smoked some Meth, and took 60mg worth the adderall. Wed night I obviously couldnt sleep so I took 40mg worth the ambien. It made me hallucinate like you would never believe, but never slept. Thur morning I saw a friend and snorted coke with him until Fri morning. Still no sleep or food, and little water. I had been drinking beer and whiskey all night as well. Fri midday I took 80mg of Oxy and about 500mg of Ultram(tramadol). I took these in the hopes of falling asleep that night. It ****** me up so bad I think I had a seizure. I came to on the hallway floor with my buddy staring at me. I had bitten a huge chunk of my tongue off, he said I had turned gray. It didnt even slow me down. A few hours later I was back smoking meth. Sat morning I found myself in a cemetary with another friend shooting heroin! I slammed 3 syringes that day and was smoking pot along with drinking heavily until I crashed around 3am sun morning for a mere 4 hours. I swear this is all fact. As I type I know it sounds unbelievable, but this was just last weekend, this has been going on for years. I need help. Ive been through 3 years of treatment. I have a good job. Im a college grad. I have a great family. I just cant quit hanging out with my "bad" friends. The more I think about it. They all have one habbit, and I have a dozen. I think I am the bad one. Drugs have taken so much from me, and there gonna take my life. Im gonna die if I cant get this under control.