Hello,
I would like to help by saying that i have just overcome a drug addiction that has plagued me for the past 2 years. It has been one of the worst experiences of my life, and has altered the world i lived him, but with the power of Christ, and with His undying love i have seen the Light. Drugs destroy lives. This is fact, they take away the very taste of life, the very good inside us. I believe that you should help this man. If you feel that you can't love him anymore, and can't dedicate the rest of your life to him, which is VERY understandable, then don't. After all, this is devotion for the rest of your life, till death would you part, marriage is still serious, it is the proposal to an eternity together. As we are one with our faith, so must one be with their soul mate. I ask you to consider the details, and carefully reconsider your relationship with this man. Then consider your love, and see what you can make of it.
If anything is true, any of these feelings, then you should find a purpose. Move forward with life and help this man in his time of need, as I'm sure he would do for you. Drugs are an eternal agonizing torment,where one is lost, but as we know through Christ, can be found again. I hope that the Lord Almighty grants you peace in this hard time.
Have Faith in God.