I just want to say if you decide to divorce your husband will, more than likely, get visitation rights and you will have ZERO control over what your children are exposed to.
If he is serious about ending this addiction he needs to agree to drop his role as youth pastor, get rid of the "smart" phone and get a basic no frills cell, and find a church with men that will hold him accountable.
If your right eye offends you what are you supposed to do? In this case, get rid of your internet! Cut it off!
And if push comes to shove, blab to the parents of the youth group and warn the woman whose phone he peeked at. Warn them! This kind of addiction can grow into something that can endanger kids.
I read a story once of a woman who caught her husband using porn. He'd gone through great lengths to hide it. She set up a trap, so to speak, and was able to see what he was doing from outside their house. When she was able to see what he was doing she got so sick and angry that she threw a rock through their window. When he ran out to find out what was going on, she ran in with another rock and smashed the computer. Don't be afraid to let that righteous indignation fly!