Then you have no free will, just the illusion of it. You cannot possibly make a choice if you are predestined to do something.
That does not compute. God's knowing what you are going to do with your free will doesn't interfere with your doing it freely. You still have to go through the decision-making processes, still have to think things through and choose, or react impulsively or whatever the case may be. Even a series of changed decisions on your part can be foreknown by God, even predestined by God, without its affecting the processes you have to go through.