There appears to be some scope for creative thinking by a lawyer on the OP's behalf. The first inquiry I would start making would be whether his ex wife had any assets when she died. Since she died only some 7 months ago her estate will not as yet be distributed and as a joint obligor with the OP her estate would have a quasi-contractual obligation to contribute one half of the payment which the government is now demanding. The law on that issue is as I recollect reasonably clear. The capital value of that obligation to contribute for the next 10 years should be worth quite a lot. The second inquiry I would start making is an inquiry into the assets of the father in law and whether there is another quasi-contractual claim against him to reimburse the payment which the OP is making to the government. The law on that is less clear. Anyway I am not a Canadian lawyer. It would be a good idea if he consulted one asap.