When one party breaches, the other party has an obligation to mitigate their damages. No court is going to make your roommate pay you for possibly several months. One month? Sure. Two months? Maybe. You can get a new roommate and then that won't be such an issue for you.
You and your roommate are jointly and severally liable on the lease, so if you are going to get evicted over this the smartest thing you can do is leave before your landlord actually files the eviction. This will save your rental history. From your new place you can decide whether to sue the roommate who left, from a position of strength. You cannot effectively be a litigant while you are living in your car.
Using Avvo does not form an attorney client relationship.