Over two drinks a night sounds problematic to me. And H and I share a drink nearly every night.
Actually, I suppose the amount doesn't really matter, it's the attitude behind it. If the person is reliant on it for any reason, then it's a problem. And the fact that it facilitates her meanness is definitely a prob.
Good luck to you, friend. This has got to stir up a hornet's nest of memories for you, from xw, and all kinds of anxiety knowing how she is going to react when you tell her.