I'm really sorry to hear about what your wife has been going through, and you yourself also. I was bulimic for 7 years, I've since recovered and what I reflect on the most now is how it seemed to stem from a lack of control. I am not sure why I felt that way though, I didn't have a life full of responsibilities, I just couldn't suddenly handle life as it was. My ED was a compulsion, without it I didn't understand who I was supposed to be. It was like I was punishing myself but also rewarding myself at the same time. My mindset was warped if I am being honest. I had CBT therapy once a week for ED for a few months and it helped me to understand parts of myself and how I thought better, but it wasn't until years later after I stopped the therapy that I really let the disorder go.
My now husband was really patient with me, met me in the thick of it and had no idea what to do. I think what helped was that he didn't give up on me, he didn't judge me, but he also didn't just do nothing. He didn't monitor me but he would listen to me, he didn't understand but he did try and he loved me.
What made me stop was the realisation that I wanted to have children and was going down a path that would ruin that. I knew I could not sustain this way of life and I wanted to let it all go. Ultimately it did have to come from me, I wish I had not wasted so much of my life though.
I'm not sure that any of this information helps, but it's honestly something I wouldn't wish upon anyone, or any relationship. The hard part is we are all different, and sometimes it's hard to pinpoint exactly what is causing our actions, to voice what we are feeling, as a lot of the time it doesn't make sense at all. Especially living in a time now where we are consuming so much information daily without knowing how to process it all. Having an eating disorder is truly running a race that you cannot possibly win. But it is also really hard to get yourself out of it.
Your wife sounds loved, and I hope this love gets you both through this.