My father in law has incured a lot of debt, in which he is having a hard time managing, he is legally separated from his wofe, but they are not divorced, my husband and I just found out about the debt, accidentally and are wondering if he passes (as he is not currently in good health) who is legally responsible for this debt?

We live in Toronto Ontario
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He debt is owed to the 407- ETR, a lean on his condo from unpaid water damage bill to the building he lives in and for illegally obtaining a sticker for his car

His estate is responsible. If the estate is not enough to clear all the debts, then they die with him.