'Cause I dug my key into the side Of his pretty little suped up 4 wheel drive, Carved my name into his leather seats... I took a Louisville slugger to both headlights, Slashed a hole in all 4 tires... Maybe next time he'll think before he cheats.

Maybe don't hide them next time, odds are you wont have to deal with the problem one way or another

Slash 2 or 3 tires, most insurance companies only cover it if all 4 are slashed.

The likelihood that she'd actually stab him is pretty low. I'd say don't bother, not because you're doing anything wrong, but because if she wanted to kill him or damage his property, she'd do it with or without the knives.

If you are sure you are right, you need to report her as being mentally unstable and have her in a temporary mental hospital. Most of the time its just for a few days, 3 weeks at most unless its too bad. In that case she would be sent to a more long-term one. The max time people generally spend in those is six months. Some people are so bad they spend most of their life moving around hospitals once every 6 months.

I feel you man. my dad does that kind of crazy sh*t