I understand, OP. I can recommend a few things.
1) Start looking for a new place to live while you deal with living with her for the next few months until you're free from that lease. Just make sure you're doing it at work or some other place away from her because otherwise I fear for your safety if she were to find out.
2) Don't take her up on her offer to replace the monitors. You don't want to give her anything she can hang over your head, so to speak. When you try to leave her in a few months, she'll try to make you feel bad and make it seem like you used her for those new monitors,
even though she's the one who ruined your old ones. It's not going to be easy, but just try to use the monitors you have. Pick up a cheap one if you can't use any of your current monitors.
3) If you have anyone that you can confide in IRL and get help from, please do. Someone that can help you move your stuff out and is also a witness to what's going on.
4) You might want to delete your browser history if she's the crazy type who will check.
Good luck, OP. Just know that your girlfriend is supposed to be supportive and understanding and able to communicate her feelings through her words—not through destroying your beloved items.