It’s entirely possible to critique white womanhood as an element of white supremacy without drawing on or reinforcing sexist power structures. You just have to make sure your story doesn’t draw its rhetorical power from isolating white women as the primary problem.
Nobody, no matter how intense or intersectional their own oppression, is immune from being a vector of somebody else’s.
In a socially stratified system, groups are oppressed at different levels of intensity but according to the same set of principles. In a matrix of domination, people are oppressed according to different principles, which makes it a more insidious tool of interfactional oppression.
I define interfactionality as conflict between subordinated groups within a system of interlocking oppressions, sown by that system as a way to subvert potential resistance to it into maintenance of it.