"That I'm taking responsibility for another person's sobriety." The crux of the core of the exact center of codependency.
It originates from a generous impulse. A caring emotion, begun in empathy, where the desire to help alleviate another person's suffering is human and humane. It becomes toxic only when taken to excess: where the other person becomes such an overriding concern that one's responsibility to oneself is submerged.
Granted I've never believed in doing things half way...
But that's unfair. To myself, I mean. There was a deeply self-interested motive for my struggle with her insobriety: I needed to put an end to her violence. If you live with someone who tries to murder you every night you focus laser-like on terminating that dynamic as your primary requirement for self-preservation. Unless you're a lot more fucked-up than I was.
Of course, many people would say that the way to best ensure my personal safety would have been to end the relationship. In the usual scenario of battered wife of alcoholic husband I'd emphatically agree. There's typically a disparity of physical strength which puts the wife's life in danger and those of her kids. She needs to get them and herself the fuck out of that situation.
Whereas in our relationship there was a nontrivial paternalistic sexism at play. I knew, and so did she, that she was incapable of taking care of herself. If I abandoned her she'd come to a very ugly place, quickly. She'd wind up on the street, in prostitution, sleeping under bushes in the park, brawling, arrested, dead behind the wheel. I responded to that insight in the way a loyal parent might respond to a mentally-ill daughter. I made the moral commitment that I would not let these disasters happen, and I stayed with her until her future safety was secured.
And so I made her sobriety my responsibility. I quit my job, made it a condition of life under my roof that she remain 100% sober. I helped her invent a small business that she loved and that at least paid her living expenses; and I followed her everywhere, literally every step she took outside the house, to ensure she was never alone in a store that sold alcohol.
It "worked", meaning, she achieved eight months of unbroken sobriety. Well — meaning I achieved eight months of unbroken sobriety on her behalf. It was still extremely stressful, but it was massively better than dodging fireplace pokers night after night.
But nota bene: this is not my recommendation to you. Having it to do over, knowing now what the experience taught me, I'd have never entered the relationship in the first place, nor offered her my guest room, nor for that matter let her learn where I lived. From my hard-won position of relatively improved mental health I will never again enter a relationship with an addict. Or a stripper, or an ex-stripper, or a narcissist, or a chronic liar or chronic manipulator. I say that, and I mean it, and at the moment I'm successfully living it. Leaving me wide open to interesting new flavors of interpersonal disaster I haven't yet begun to suspect.