All perfect praise be to Allah, The Lord of The Worlds, and may His Peace and Blessinsgs be upon our Prophet Muhammad and upon all of hsi family and companions.
Riba-based loans obtained from non-Islamic banks are prohibited, and this is a well known fact to the general public, so all the parties involved in this transaction are sinful, be they creditors or debtors.
Jabir Bin Haya`an was reported to have said: “The Prophet (PBUH) cursed the one who took or gave Riba, the one who did the paperwork, and the two witnesses. He (The Prophet) said: "all of them are equally cursed.” {Muslim/pp.1598}.
Repentance from such a great sin should be through showing remorse, asking forgiveness, and abstaining from such an act. Allah, The Almighty, Accepts sincere repentance from His servants, and He Says in this regard (What means): “He is the One that accepts repentance from His Servants and forgives sins: and He knows all that ye do.” {Ash-Shura/25}.
However, you have no choice now but to settle the regular payments of that loan. Moreover, you aren`t obligated to shoulder an extra burden by borrowing money in order to speed up payment so as to decrease the rate of the usurious interests. In addition, you aren`t obligated to sell the house that you have built because the sin of Riba is incurred by the person who committed it, not what he had spent it on. And Allah Knows Best.