Your Dad was once a teenager also, and I'm quite sure he made a few mistakes himself before becoming an adult. Sure, he's likely to be upset when he first hears of this, but what you tell him, and what you do afterwards is going to make all the difference.
I would consider calling him and telling him. Let him know you have some bad news to tell him before you tell him what it is. Tell him you know you made some very bad decisions and that you are sorry for disappointing him. If my son called and told me like that it would be the easiest way for me to get the news.
The fact that you care so much about what he thinks says to me that he is probably a pretty good guy. It also tells me you’re not such a bad guy yourself. Make it as easy on both of you as you can.