How can one act concerning an usurious loan that was paid as a down payment for an apartment, knowing that the bank will deduct the full amount paid in case of return, given the dire need for money to complete the marriage and to avoid continuing to deal with usury?

Consuming and dealing in usury is one of the gravest major sins. Allah has forbidden it in His Book, in the Sunnah of His Prophet, and by the consensus of the Ummah. Among the proofs of its prohibition are the Almighty's saying: "But Allah has permitted trade and forbidden interest," and His saying: "And if you do not, then be informed of a war [against you] from Allah and His Messenger." In the Sunnah, the Prophet (peace be upon him) said: "Allah has cursed the one who consumes usury, the one who pays it, its two witnesses, and its scribe, for they are all equal in sin." One who repents from usury must return only the principal capital without the interest, as the Almighty said: "And if you repent, you may have your principal - [thus] you do not wrong, nor are you wronged." If you are compelled to pay the usurious increase after sincere repentance, regret, and determination not to return to it, then there is no sin upon you.