I broke my girlfriends phone to stop her from looking at it

I broke my girlfriends phone to stop her from looking at it and I regret it. We've been together for 3 years and recently I told her that I had an issue with her always being on her phone but I never broke it. I wanted to do something more drastic to express my feelings, so I shattered her phone. Now she can't use it and we're constantly arguing. I feel terrible about my overreaction and I don't know how to fix the situation.