The will names an ex-spouse. What happens?
When a will refers to an ex-spouse by name, the will is considered revoked as to the ex-spouse only. That is, they will not inherit anything from the property of the estate that goes through probate.
Note that there may be provisions in the divorce decree that give the ex-spouse certain rights to retirement accounts, but retirement accounts are not usually part of the probate estate because the funds pass by contract (beneficiary designations on the account).