Of course it's a great help that they know!
My own wife knows every detail of my sexual acting out history and I share my recovery with her in any way she asks me to. If c"v I acted out, I'd tell her right after I told my sponsor...because she asked me to tell her this stuff!
When it all started, 20 years ago, I lied to her constantly, as most of us do. When I got caught by her (for the 5th time) about 17 years ago, I told her the roshei prakim...I finally got real help a year later when I hit bottom. I got sober and started recovering.
Two years ago I spoke at a shabbaton of about 200 frum sex addicts (mostly kollel and chassidishe yidden), telling my entire sexual acting out history, how I hit bottom, how I came to recovery, and life has been like since then, be"H. Many of the guys' wives were in attendance and heard the whole thing. At the time I was sober for 13 years.
When I got home that night, my wife told me she wanted to know as much as anyone esle there now knew about me, too. So I sat down and repeated the entire disgusting - and beautiful - thing, to her that night.
It was a catalyst for a much deeper marriage.
But that was 100% because G-d was in charge of the timing, not me.
My only point in the previous post is that the fantasy of using our wives as sponsors or gedarim against addictive behaviors is torture and does not usually work. It is not a real solution, besides being cruel.
But by all means - it's still true that telling her everything does help at least in the short term!