The interplay of divorce and validity of wills is difficult law at best. I would not investigate this alone. In Michigan a spouse can take against a will in most situations. Get a probate attorney, present the will and get a more detailed opinion than what can be given in this type of setting.
Does the WIll make any difference? If all of the assets were jointly held, then the Will is irrelevant. You need to review this with an attorney to figure out where you stand.
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I agree with my colleagues that it is critical to deal with someone local to see where you stand. Here in Massachusetts, if you had a divorce agreement and it was signed by the parties and approved by the court, we then have a 90 day window before the divorce is technically "final", an old Puritan practice hoping for reconciliation. Nevertheless, the agreement, as a contract, became binding once signed and approved by the court, so the agreement overrides the will and I believe joint property arrangments that the agreement may have terminated. I presume the will and agreement are at odds. If there was jointly owned property, I trust the agreement dealt with that.
To questioners from West Virginia & New York: Although I am licensed to practice in your state, I practice on a day-to-day basis in Massachusetts. I answer questions in your state in areas of the law in which I practice, and in which I feel comfortable trying to offer you assistance based on my knowledge of specific statutes in your state and/or general principles applicable in all states. It is always best, however, to work with attorneys and court personnel in your own area to deal with specific problems and factual situations.