Ditto what IOAA said.
You say James: I want the relationship to work, but don't want to face the fact that it won't if we/she carries on drinking. Right now I feel like my entire life is in the hands of other people and it's driving me nuts.
You shouldn't put your life in the hands of others. No one can make you quit drinking unless you want to and if you are ready, DO IT! You may very well have to let the relationship go. If she is fine with her drinking and chooses booze over you, than I don't think holding onto the relationship would be worth it anyhow. Do you?