One of the tougher Q & A's
A: Good question!
Isaiah 46:10 I make known the end from the beginning, from ancient times, what is still to come. I say: My purpose will stand, and I will do all that I please.
In specific, His plan regarding Christ worked out just as He planned. God's plans cannot be frustrated, so the evil done at the cross didn't frustrate, but rather accomplished God's purpose.
Acts 2:23 This man was handed over to you by God's set purpose and foreknowledge; and you, with the help of wicked men, put him to death by nailing him to the cross.
Acts 4:27-28 Indeed Herod and Pontius Pilate met together with the Gentiles and the people of Israel in this city to conspire against your holy servant Jesus, whom you anointed. 28 They did what your power and will had decided beforehand should happen.
Two things are clear. God decreed or ordained the evil and the people were held accountable for it. At this point you have to remind yourself that God can't stand evil.
Habakkuk 1:13 Your eyes are too pure to look on evil; you cannot tolerate wrong.
So we know God doesn't do evil by decreeing evil.
He is, by definition as the one who plans it, the ultimate cause of everything that happens. And, thus, is the ultimate cause of evil. Yet without himself doing or being evil or approving of evil. In other words, He decrees things he hates and disapproves of.
That's the best I can do. I think you have to say what the texts say. People are so quick to "protect" God that they are hesitant to make evil part of the decree. I think you have to say what the text says whether you understand how it could work that way or not.