That's not the central problem, the widowhood. It's that through some shenanigans (and lack of alternatives), she's her father's heir. Installed and everything. And this woman is, of course, no longer the consort but the. . . .
Well, I used dowager automatically. It is the English word.
The lady dowager facing off with the new lady regnant, who now has the power that the lady dowager had had, only weeks earlier.
Five seconds after calling her that, of course, I start to wonder whether there's a dower involved. And whether my heroine, if she only had enough time, could pack this woman off to her dower lands and tell her to stay there. In which case, she can dream about it while she's busy. And perhaps return home to discover that the woman packed her bags and left of her own accord, knowing the heroine could return to eject her at any time.
Ah, how economics can ramify on its own accord. And complicate a relationship.