Is it riba (a major sin) to have a mortgage from before I converted to Islam?

Bought a house over 10 yrs ago on mortgage. I became a Muslim several months ago. I know riba is haram but I cannot sell the house because the other co-owners do not want to sell. I also signed a 2nd mortgage because the co-owners needed to close old debt account. If I didn't sign, the 2nd mortgage would not be approved. I don't have anywhere else to live for now. I repented but is it enough as riba is major sin?