I am so sorry for your loss. Your post is so beautiful yet so sad. It shows what a healthy mature individual you are, in that you saw all the healthy parts of your ex wife that existed along with the unhealthy parts of her disease.
One thing stood out for me:
As a Christian I struggle with God's purpose in alcoholism. XAW was traumatized in her childhood, I will never know what it was. She believed in God and Jesus and forgiveness and during her clear moments, I saw a beautiful, child like faith in her. She loved going to church and she acted more like Jesus than 99% of people I have met.
FWIW, my opinion is that God doesn't have a purpose in alcoholism, just like He doesn't have a purpose in cancer. Diseases are not of God. They just "are". Man made, environmental, or "egoic lies" (or whatever word you want to use) based. I just don't see it as God deciding who is going to have alcoholism, who is going to have cancer. I see alcoholism as us humans being in pain, and turning to a poison that lies to us because we think it's helping us feel better. I see alcoholism as us turning away from God, because we're believing in that false alluring power of alcohol. We don't even realize that the Power of God is what can help our alcoholism and pain from what caused us to drink in the first place.
I don't think God has a purpose, either, in trauma happening. I think trauma is just another example of humans being separate from God, doing their will instead of doing His will. It's the reminder that God gave us free will as a gift, but it's up to us to use it according to His will.
That being said, there was a purpose for her life, and that is to be a witness for God's love. In her memory we can all try to be better people like she was. And to remember that alcoholism is a disease.
Again this is just my opinion I thought I'd share. I'm not saying it's right. I'm not even sure the words I'm writing are matching what I'm trying to say. But I hope that it helps in some way to bring you a sense of peace.