I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear that this happened.
First of all, if you and your roommate had an agreement that rent would be paid, your landlord has no legal authority to release your roommate from it. They could agree to let the roommate move out without penalty, and could agree to reduce your rent as a result, but the landlord can't say, "Okay, Betty, you're allowed to move out, and Barney will have to pay all your rent now" (unless there was domestic violence involved). You can still sue your former co-tenant for unpaid rent until you found someone new to move in.
False light is a type of invasion of privacy. When someone disseminates information that is technically true but presented in a false light, and as a result harms the person's reputation, the injured party may be able to sue for damages. A false light claim carries both pecuniary loss, plus punitive damages. However, that requires a widespread dissemination, not a comment to one person. But you could sue for intentional interference with contract or defamation. So those are three separate theories under which you could sue the former co-tenant. That's the person who injured you, not the landlord.
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