Oh, sweetie, don't you think that if we had that much power of someone's choices that this board would not exist? Because then we could all stop the alcoholics in our lives from drinking and all would be hunky dory.
He had choices. That he chose to use (if, in fact, he did) is on him. And if he is blaming you for that choice and you are blaming yourself, then what do you envisage your future together to be? One of sweetness and light and love or one of tip-toeing around and blame-shifting? ETA: I have just read back to your first post - he had even more choices than most. He had a whole support network around him - his sponsor, his retreat contacts etc. Why would this be laid on your shoulders?
Can you seek out some support in real life? Friends, family or al-anon, perhaps?