Does Illinois have Jurisdiction for your divorce?
Either party must have been a bona fide resident of this state for 90 days prior to the filing of the complaint, which must be stated in the complaint and proved at the final hearing (Drivers License, etc.). If both parties currently reside in the state, then there is no time period required.
If you have minor children living with your spouse in another state for over six months then you should consider filing in that state as that court has jurisdiction over the children. Your spouse can waive that jurisdiction in writing.
You should file the divorce in the county where you presently reside, or in the County where your spouse resides, if she lives in another County. You or your spouse must have an Illinois address in the county where you are filing your divorce. Illinois civilian residents living overseas may file in Illinois if they have maintained their residency in Illinois.