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At the time you filled out the initial financial forms, your wife had not passed away, and therefore, the insurance policy was not in effect. Thus, I don't think you've got a problem there. When you received the money, you may should have informed the PO that you could pay for the classes based on this recent income.
My suggestion is to volunteer to pay for the classes, and reimburse the state for any money already paid over on your behalf. I don't think this will be considered a violation of your probation. Just try to make good on the payments and ask the PO to give you a break.