بسم الله الرحمن الرحيم
(Fatwa: 129/85/SN=2/1439)
As it is haram to take interest in the same way it is also haram to pay interest. You did an unlawful act by taking interest based loan. However, let gone by gone. Do taubah seriously. Try to pay the installments as soon as possible. If a man does true and genuine taubah Allah forgives his sin no matter how big is it.
التائب من الذنب كمن لا ذنب له (ابن ماجه: 4250)
The one who repents from sin is like one who did not commit it.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband