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Hello and welcome! My name is ***** ***** I will try my level best to help with your situation or get you to someone who can.
Are you under one lease together or do you each have your own separate lease?
Have you pursued subleasing your spot with any of the 17 people who responded to your ad?
Ok, I am a little confused because if your landlord allows changing co-tenants, then you could simply have an interested party substitute in as a changed co-tenant. It would even be better for the landlord if he agreed to allow you to sublet because you would still be on the hook as the primary tenant for any damages or delinquent rent if the sub didn't pay.
It would be up to the landlord as to whether to allow this or not, but as a landlord myself for over 26 years, I don't see a downside to this for landlord so I would suggest discussing it with him. I would tell him that otherwise, you will have to breach the lease and then he would end up evicting the other tenant, lose rent, have to re-rent it, and then pursue you and co-tenant for any lost rent..
Ok, that makes things more difficult if everyone has to agree.
With that said, if the subleasing idea is out and the landlord won't agree to it, then your only other option is to just breach the lease and if the roommates sue you, you would have to defend on the basis of a "constructive eviction" which is where they make it so uncomfortable as to essentially force you out.
You would need to document what they did while it is fresh in your mind now and keep that handy to use as evidence if they actually sued you, which is probably pretty unlikely based on my experience. Typically they will just find a new roommate or just pay the rent themselves so they don't get evicted. In order to sue you, they would have to have you personally served with a summons. And if they don't know where you are, it is hard to sue you if they even bothered to try.