What you typed is actually 90% of a good C+F addendum. Here are some edits.
Throwaway23245 wrote: When I was 18 (ten years ago) my friend and I got in a verbal fight argument with someone at a party so we were kicked out. He We decided to steal the kids laptop and iphone to get back at him (which he mistakenly damaged in the process) and because we left and he stayed at my house that night, I was also arrested and charged with 6 felony counts (2x burglary, 2x grand larceny, 2x felony vandalism). The charges were ultimately reduced to one count of misdemeanor vandalism only to which I pled no contest, and everything was dismissed after 60 days pretrial probation. It was foolish . . . And I have changed . . .
Obviously you also need to clean up the grammar and style. But if you did, this would be a pretty perfect addendum. Even if you decide to rewrite, this paragraph strikes the appropriate tone and runs the appropriate length. The facts as you've given them shouldn't require more than one paragraph.
Don't go overboard on the steps you've taken to better yourself or on how you're a different person now. Maybe one well-written, mature sentence each. Or even better, one sentence total. Lots of addenda read like "I DON'T even KNOW who that person WAS!!!" That's not a good look, especially for something minor like what you've described. You do want to take full responsibility, but you can accomplish that by changing the pronouns as I've done above. You don't need to say what the argument was about. You might consider mentioning that you've been in contact with your state's bar. You don't need to say more than that (or even say it at all), but if you can do it well it will show you're approaching this responsibly.
Do pay very close attention to the way the C+F questions are worded. I just checked my Harvard app and KJ is right that you don't need to disclose any of this to them (assuming the language is the same). My app doesn't ask about arrests and says to omit misdemeanor convictions that are more than five years old. Though to be clear, you'd omit because that's what the app says rather than because that's what MA law says. Also, I don't think most schools ask about charges in the abstract, so you may get away with not mentioning the felony charges. Again, just pay very close attention to the questions' wording.
This should not prevent you from attending a good school, and it should not keep you from being admitted to the bar. Good luck!