Help me find

Fl a saint but an orphanage (?)
She got adopted by a duke since the duke house has to do it because if she is adopted by the king then they would have too much power and can wipe out the duke house and also the church is evil side too.
She then have 2 step bro, 1 step bro liked her but it's more like obsessed than like, the other is the ml.
I remember one of the plot of the recent chapters be4 i lost it is that she got ppl questions if she's rrl the saintness cus she lied to ppl that she alr lost her power yadayada, and she decided to prove by suicide in front of everyone