What, exactly, are you confused about?
You have a history of letting her down in a huge, huge way. No, let me rephrase that. You have a history of stomping her trust into the mud, kicking it in the stomach repeatedly, setting it on fire, and then pissing out the flames and taking a dump on the ashes. Do you really expect her to stand on the edge of a muddy patch and hand it back to you to see what happens?
I know that sounds really harsh, but what you did to her was much harsher. You may never fully understand how deeply and fundamentally you let her down. And you certainly won’t understand it as long as you’re talking about how her being out of town sent your use soaring, and how you’ve been totally completely utterly clean (except for using last summer, but that was only a tiny little bit of something pretty innocuous), and how you (singular) bought your (plural) first home last year. All that stuff indicates that you’re not really taking responsibility for your bad actions, and are taking way too much credit for your good actions. In short, I don’t really see any indication that you’ve made the fundamental sort of mental changes that will make the behavioral changes stick long-term.
It’s probably not disgust, per se, that she feels toward you. More like resignation, because until you change your head, it’s just a matter of time till you let her down again.
Or maybe it is disgust. Sometimes you just can’t really process all the negative feelings about some disaster in your life, so you cruise along thinking you’re coping just fine, and then at some point down the road all that grief and anger and pain gang up and just fucking waylay your ass. Leigh may be having some of that going on, and you’ll just have to sit down and shut up and let her work through it for as long as it takes. You owe her that much, and a whole lot more.
Or it’s possible she’s one of these codependents who like taking care of various types of ne’er do well like addicts and the chronically unemployed. The fact that someone isn’t stuffing the rent money up his nose isn’t necessarily a clean bill of psychological health. Sometimes, when the addict in such a relationship gets clean and starts rebuilding his/her life, the relationship falls apart.
Regardless of what she’s really feeling or why, all you can do is to keep on keeping on. Continue the hard work to get totally clean and rebuild your life, not for her or for your relationship, but for you.