Logically, if a choice is foreknown for certain, one cannot choose otherwise, your free will is a illusion.
No. It's not a logically compulsory inference that just because I know something about your future that you don't,
...then therefore your freewill is nullified.
In 1885 you and Marty McFly both have free will.
Marty travels forward in time and learns that you freely chose to marry the local school teacher.
You don't know that he now knows this fact.
You remained in the 1885 old west. You haven't even met the school teacher yet. Your free will choice to marry or not marry isn't compelled by Marty's time travel insights.