One thing I learned in my life is that no woman on the planet is worth doing anything like this guy did. If you have proof positive she's cheating on you for no good reason, dump her cold, completely disassociate, and send her the evidence. She can't be that special if she's going to act like some dog in heat.
If you are stupid enough to live with a woman before you are married, keep everything in your name with no joint possession of anything, especially where you reside. Make sure she moves in with you and not the other way around. That way when she cheats you throw her sorry ass out in the middle of the night, possessions and all and leave her to fend for herself, even if she doesn't have a damn dime to her name.
Change the locks, change your number, move if you have to, and leave her no way to contact you. Put out a restraining order if you need to. If she ends up in jail because of her stupidity, so be it. Run and never look back, because 9 times out of 10 they'll run back to you once the magic is gone. If you take them back, they'll do it again.
Ladies need to do the same if in that situation. And if he's violent, get a gun and put one between his eyes if he tries to hurt you.
If everyone took that attitude, there'd be a great deal less of these kinds of situations in the world.