We all agree there was divine foreknowledge.
The essence of free will is that foreknowledge does not translate into taking over the will. For example, a parent may foreknow that his adult child is making bad choices in life, yet he respects the choices for the sake of the child himself.
The Scripture teaches with great clarity that both in the case of murder of Abel and of the redemptive work of Christ culminating at Calvary, God did not take over the will of the evildoers. Cain is depicted choosing a poor sacrifice, then killing Abel out of envy. God is not shown to instill these choices into Cain. The Crucifixion happened as a complex interaction of human wills, punctuated by choices of individual players and culminating in the direct choice between Christ and Barabbas, exercised by the Jews. Christ, dying, described God as abandoning Him, rather than killing Him. In both cases we have God allowing human will to be exercised, then taking his turn to exact justice and do other good.
And just how was Judas benefited by God respecting his "choice" to betray our Lord?
When the Bible says that God hardened Pharaoh's heart, it is clear that Pharaoh's will was being driven by God's plan and purpose. Where did Pharaoh's free will come into play? If Pharaoh's will was inviolate (as some of you Catholics insist) then God would not have been able to harden his heart. Nor would he have been able to soften yours. Your free will is not sacrosanct. God can mold you anyway he wants to. He can make you into a vessel to demonstrate his mercy or he can make you into a vessel to demonstrate his wrath.
While Judas' choices may have been of his own free will, God clearly placed him in the unique position where his destiny as the Son of Perdition was sealed from the foundation of the earth. God chose Judas from the foundation of the earth for a specific purpose and his purpose was to use Judas as a vessel of wrath.
What is his purpose for us? Something to ponder.