My heart breaks for you too....I've stood watched, waited. I've rescued but learned that I can only rescue me.
Maybe in your image place a rescue raft within his reach....AA, NA, or any of the other programs and imagine that all he has to do is to reach out and grab it, hold it tight....and imagine that he can't or won't for what ever reason....he's not afraid yet, not tired yet, or can't see the raft or the danger.
Prayers for strength,
qwer