If a person has already gotten into a situation of a house mortgage and was the middle of paying it off, how would one after repenting and making dua to Allah get out of this situation? Should they pay the rest off or sell their property?

Ustadh AbdulAziz al-Haqqan

No need to sell, repenting to Allah is enough. If you are capable of only paying the debt without the interest then do so, if not then you are forced to pay it off and Allah knows best.