You did the right thing by expressing your opinion but also accepting you can't control what your STBXW decides.
My STBXW are almost 2 years into this thing and we haven't separated finances. Buckle up and hang in there.
I sense you are worried about your STBXW getting triggered and things blowing up in settling financial matters. You can only control your part - you could do things perfectly and she still could blow it up. As a D'ed friend always reminds me, "She has her own narrative, she is operating on emotion."
Kudos to you for standing your ground on what you think is right.