I am happy that he is trying at last. It will be no simple or quick cure for a man who has been addicted for decades. Addictions take on a life and very strong energy of their own, like a separate being. (In fact, I suspect that there are other beings present among addicts...) The destructive atmosphere around many addicts is far beyond anything most people have ever experienced. It is close to the darkest realms of hell itself, and it is no easy feat to climb up out of there. Most addicts try many times before they stop and most don't unless they go through some type of serious life event. They also become masters at manipulation and deceit, even if it isn't in the nature of the person, it is the nature of the drugs. There is no end to the mind games that living with an addict will throw your way. What is his drug of choice?
I understand you wanting to help him. The fact is that each of us have to grow on our own terms and in our own time. We can't all reach enlightenment at once, although it would be wonderful if we could. I have to remind you that you need to stay strong yourself first. You have to learn what's good for you first. I know you need, and have always needed, a father. Some of never get to have that in the way that we need, no matter how hard we try and how much love we send out or how much we try to fix things.
Addicts do have great self-loathing, severe deeply rooted depression and are deserving of our greatest compassion. We are all connected in this universe.....yet we are also separate, sovereign individuals. Tolerating abuse or neglect of ourselves for the betterment of another is not something to be desired. Although usually when we help other it is also helping ourselves, it isn't always. Helping others without any desire to help ourselves is the ultimate goal, but only when you are not placing yourself in peril. Please protect yourself.
That's just my opinion based on 17 years spent trying to help someone that almost ruined my life and a lot of time around addicts of all sorts. I also had an emotionally absent father who I tried to get to love me for far too long. All situations are different, tho. Sometime we have to follow the darkest paths for the lessons we need, unfortunately. You can't walk another's path for them, only offer love and support, sometimes best at a distance. I hope it will work out for your dad, just please be aware of what you're into.
Sorry to have the negative outlook here. Having come through the whole martyr experience, I would like to spare anyone I can. I think most of us who come from dysfunctional homes have a desire to fix things and people. It is a lovely attitude held by beautiful souls... as long as you remember that you are number one!