What is the ruling on using haram bank profits to pay a down payment for an apartment, and what are the implications for the wife who did so, and what is the optimal course of action in this situation?

It is not permissible to leave funds and interest in a usurious bank except out of necessity. Usurious interest must be disposed of immediately in its available channels. The desire to reserve an apartment or the existence of a penalty clause does not permit benefiting from usurious interest unless you are poor. Rather, the required amount must be secured through permissible means or the penalty clause must be borne. The wife must repent and dispose of the usurious interest in its rightful channels.