I am recently separated, my ex wife negotiated a loan from her father 6 months before before the separation. I told her not to do it (knowing marriage problems and it wasn't fair to her father)but she took the money anyway. I didn't sign any papers or agreements and now two years later,paperwork shows up saying we both must repay. Other than a moral obligation,

1) Can I be legally forced to repay ?
2) Our marital debt was already calculated and paid and this debt came up after the fact months later.

Canadian Law...

This all came about after I mentioned equalization of net family property(her company RRSP)

There are two issues to be considered. Do you owe a debt that you did not negotiate, that you warned against and for which you did not sign? Did you benefit from the transaction?

Based on your version of the events, if you were sued, it is unlikely she would succeed. She could not obtain a judgment against you for your share of the debt.

However, if you benefited from the transaction (paid off your credit cards, paid off joint debt, improved jointly owned assets, etc.), it might be taken into consideration in determining if you are entitled to her RRSP in the equalization of assets.

This is precisely why the issue was raised. It up to you how you wish to proceed. If her family wished you to responsible for the debt, they should have made you aware of the details and had you sign something. They were probably aware of the marital issues and chose not to. I do not believe it is they who are raising the issue but your wife or most likely her lawyer to scare you away from a share of her assets.