Detachment means "letting go of the outcome." So if it feels like divorce to you, it's because you're afraid that in letting go of the outcome, divorce COULD end up happening.
And of course it could. But it doesn't HAVE to, and truly detaching is the only way you have to save yourself OR your marriage.
It's the whole "free the bird" thing -- if you cage it, it was never really yours to begin with.