Hi, Hopeful,
Hard not to get all spiritual, given your question, but I'll give you my take on this, which applies to life generally. First, I don't think anyone's life lessons are the same as anyone else's, so what you take away from this experience is not likely to be exactly the same as anyone else's take-away. Everyone has their own personally specific lessons to learn. But more than anything else, I think that dealing with an addict teaches about the nature of love - unconditional vs. conditional, healthy vs. co-dependent, self-love balanced against love of others. Also, the experience hugely strengthened my relationship with my HP, as I have had to reach out daily for support, guidance, courage, and strength.
Second, I don't think our experiences in life are only about lessons for US. I think that often we experience things so that we are better equipped to impact others in a positive way. What you are experiencing with your ABF and what you are learning puts you in a unique position to empathize with and understand the pain and experiences of other co-dependents, addicts and addictive behavior, and probably a whole host of other difficult situations endured by people you may come into contact with in the future. We have no idea right now how our experiences and growth may give us resources to help others and impact the world in the future.
Finally, as Scott Peck in "The Road Less Traveled" said, "life is difficult." Our greatest opportunities for growth - emotionally, spiritually, and intellectually - come from being faced with tremendous challenges and learning how to deal with them. We grow so much more, and as a result have so much more to offer others, through dealing with tough situations than we do through happy times. Our happy times are our respites - our little vacations - from the school that is life.