To the OP,
First, while others are going to disagree with your smashing ways, at least you took the first step towards following through what the house rules are . . .
Now, admittedly, this is a bit too extreme and their is no turn around point. I suspect that your divorce, like most, didn't end with kumbayah singing and dancing together. There were probably lots of disagreements leading up to your divorce and your son noticed. Perhaps you are currently amicable with the wife, but your son is dealing with a lot more than you think. His whole world is not divided among multiple dwelling and his safety net, his parents, are now divided.
Your son needs to spend quality time with you. You need to be the bigger person and go and open up the conversation between you to. I wouldn't harp too long on the smashing as that will just bring up unpleasant memories for both. Instead, focus on a building the relationship and a way to have your son "earn" a new one.
After you have tried to build the relationship by spending time with your kid, then set the ground rules, stick by them, and be the calm, collected father figure he needs. Kids crave stability and normalcy. His normal is uprooted and his mechanism is to not deal with it and try to put it aside by distracting himself in the virtual world. He would rather ignore his current situation than face it, understandably so.
I would strongly suggest that you both go to therapy together or meet with school counselor. It may not be possible for you to break through alone. Also, keep it mind that building a relationship again is going to take time and energy. Obviously, you were already in the hole before this smashing incident so put yourself in his shoes. Explain to him how much pain your are going through too as well. Divorce is rough for everyone.
Good luck! Focus on the future. We all make mistakes, none of us are perfect.