An inheritance is generally treated as separate property and not subject to division in a divorce. The exception would be if you co-mingle the funds. For example, if you take the inheritance and use it to pay off joint debts, or buy furniture for the home, or even just deposit the money into a joint bank account, your spouse can then argue that you have made it a marital asset, and that they are entitled to a share.
Forging your name on the loan is fraud - it's a criminal act. I don't know when specifically you found out about this, if it was just recently or not? You could report the matter to the police, and should also report it to the lender and see what instructions they give you. Given that 10 years has passed, it may be too late to hold him criminally liable. I do think you need to include a provision in your divorce settlement that he be fully responsible for the loan. The problem is that such an agreement is between you and he, not the lender --and so long as they think it's actually you who signed it, they can pursue you if he stops paying, which is why I suggested you contact the lender as well.
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