He's going to be raped in prison on a daily basis for the next 30 years (if he isn't 'shanked' by his fellow convicts). I'm sure he regrets his actions, as do all criminals who were sure they were not going to get caught.
He's a media darling so he'll be protected in jail until the trial. That narcissistic sociopath doesn't regret anything. He was born into wealth. He is certain that sympathetic jurors will let him off the hook. All it takes is one.