I can't pretend to know what you are going through and of course my thoughts, hopes and prayers that everything will turn out for the best are with you as well.
I'm sure you love him, but alcoholics and drug addicts always say they are sorry... and yes, they probably do mean it. Unfortunately as you have found out time and time again, the love and physiological need for drugs may surpass the love and physiological need he has for you
Getting out of even an abusive relationship (which this is...even though it may not be physical) is very difficult and only you know what is right for you. You deserve to be loved. You deserve to have someone to grow old with and most of all, you deserve to be happy. Time will heal your pain if you decide to leave, but of course that will be an EXTREMELY difficult move.
I can't imagine a life where a husband is sucking all the goals, dreams and happiness out over addiction, but it happens all too frequently.
Good luck and God Bless.