Doing Time - By an ex-prisoner 'Lauren'

Names have been changed to protect the author's identity. 

Dear Prison Widow. I have recently been released from prison. Three weeks in to my release; I feel like I do not fit or belong in society.
I am 33 and have been in and out of institutions since I was 19.
Nearing my release date; I always have positive visions of what I want from life on the outside but I can't get there.
I have been clean (heroin) for 13 months and have taken part in many drug programs whilst I was in prison; but as soon as I get back in to society; the demons get the better of me and I start using again.
I know some of your readers won't have any sympathy for me and in a way they are right because I can only help myself. The problem I have is saying no and because I am a creature of habit when dealers see me in the street or know when I'm out of prison; I fall straight back in to their hands and back on to the beat. (red light area)
A lot of people say it's easy to blame the way I am because of my past but I don't know; or haven't been given the opportunity to know any different. I just can't set myself free from the system. It draws me back every time and in a way I am safer in prison. Being in HMP gives me structure; routine and it's a safe place for me to be away from people who target me on the out. I'm not saying prison is a lifestyle that is right; but for me it provides normality because I have never had normality in the outside world. 
Some people say I should move areas away from all my acquaintances but adding to my addictive personality is bipolar and uprooting to a strange place isn't that simple for me. I just keep going round in circles and right now I have plunged in to a depression because I am missing prison. How sad is that? It is pathetic isn't it; but it's how I feel at this moment in time.
How can prison rehabilitate me when all I want to do is go back in there? 
Sorry for rambling on; I just wanted to offload and find out if there are any ex-prisoners who feel the same as I do. Love from 'Lauren'.