When someone breaks your heart, they smash it with a sledgehammer. You see what I’m saying? That’s just a metaphor. This chick isn’t satisfied unless she literally hammers something of his, such as his brand-new Audi, to make peace with the fact that their relationship is over.
He ruined the relationship with his cheating and lies, so she decided to do the same for something that was just as vital to him. This is an awful — and illegal — thing to do. It’s really terrific revenge. Even if her boyfriend didn’t care about the connection, his heart would be broken regardless.