If she truly repented at the last moment, with perfect contrition, she'd be inside the Church. Not outside.
That's astronomically, ludicrously unlikely, but we don't have the certainty of faith that she didn't.
That's not the way it works. While we cannot have certainty of faith that she is in hell, we have the use of reason for a reason.
We should never speculate more than an instant, then shutter to think that anyone who lived their whole life outside the Church, who hated God and his commandments their whole life right up until her death - and used her authority to further the implementation of abominable things into the law of the land, could even possibly, maybe, perhaps who knows?, might have repented at the last moment and was saved.
Rather, better we use her as an example and tremble for the fate that she chose for her eternity during her life, right up until her death - and because she chose it, she now suffers unbearable torments forever and ever. THAT'S how it works.
We are not pronouncing judgement, we are using her as an example as to why we are not to live according to the way she lived - and died.