What on earth happened?

Hey everyone, sophomore in OSU here.
I only really got into college football earlier this year, but I’ve completely fallen in love with Buckeye football ever since.
I was watching the game in my apartment today. We went up 10-3 early, the energy was unreal, and Texas looked completely lost. I genuinely thought we had the game in the bag, so I turned it off to handle some stuff.
Just checked the final score and my jaw dropped. For those who watched all 4 quarters: what actually went wrong in the second half? Did Texas completely adjust, or did our offense just stall out?
Also, forgive the newbie question, but do we have a realistic shot at a revenge game against Texas in the 12-team playoff later this season, or are we done seeing them this year?
Go Bucks, but man... definitely learned my lesson about turning the TV off early.