Well good on you for writing it out and posting it--one of the worst things is isolation in your misery and even more problematic is the sense of fultility and despair that sets in. There are a million statistics out there to make you feel even worse--you will hear from all directions how 12-step programs don't work and rehab doesn't work and on and on. My take on it is that any program "works" if you are willing to put your heart, mind and soul into your own recovery. You don't have to get fanatic about any particular dogma and you are free to integrate what actually feels positive for you.
You can recover--this much I know. It's hard at first, but gets easier if you make sure that it isn't only drugs that you are recovering from. You have to get down to the roots of why you wanted and needed the drugs in the first place--because usually there was a very good reason and drugs helped in the short term. Every single person born has to work to put together the big three:mind, body, spirit and to create a life that is satisfying and meaningful to them. It takes a lifetime to do this but if you can get away from the ideas of perfection and the ridiculous prescriptions of the larger culture (that you should be happy and secure all the time or there is something wrong with you) then you can relax into being who you are. It becomes somewhat of an adventure to get to know yourself. Most of us spend a long time running from who we are. Maybe we got shamed for it along the way. But the best thing you can do for yourself right now is to say, "I made some wrong choices but I can understand why I did. Shame and regret will only bog me down. My life is worth saving and that is where all my energy is going to go. If I try and then relapse I will get right back up and try again. My life is worth saving." Make that last line your mantra until you truly believe it.
Lastly, get support from every direction that you can--family, clean friends, organizations, community services, churches (if that's your thing). Support your spiritual understanding of life. I'm not a believer in any god myself but I know that I would not have had the strength to make it through the hardest parts of being human without trying to put my experiences in a larger framework. I believe this one life that we miraculously are given is not all there is. There is a great web of existence that we are all part of. What we create in our minds (while we exist in these bodies) is a part of all creation. That is my guiding principle and it gives me the strength to have compassion for myself and for others--even when it feels hard to do that. Buddhists say that having compassion for your self is the most difficult. It's not something you can develop overnight, it's a practice that you work on step by step, day by day.
I hope I have given you some hope. I have total faith that rehab can work for you if you are finally and completely ready to recover. It will take everything you have in you, but imagine the joy and empowerment of experiencing everything that you do in fact have in you. Check out Tommy Rosen's writings, Gabor Maté's writings, Ted Talks (lots of inspiring ones). Understand the larger context for addiction and then your own personal context. Talk to all the other good folks on here that are struggling, too. Pm me if you ever need anything.
