My bipolar roommate had a manic attack and was convinced that me and some other people were plotting against her (we weren't). She started accusing me of absurd things like going into her room and rearranging her belongings. She checked into a psych ward for a few days, but when she came out, the threats got worse--for instance, she said that if I was in the apartment when she got back, she would call the cops, or she was going to have a former navy seal escort her there and physically remove me.

Our grad school spoke to her parents, asked her to leave, and offered to let me stay in a dorm. I called to our landlord (who owns the condo)--I asked him to let us out of the lease. He agreed over the phone, so I signed a lease to a new apartment. Then I got an email from my landlord saying that he wasn't going to release us from the lease after all, and I had to continue paying rent until I found new tenants.

Then my roommate decided she wasn't going to move out. Instead, she said she was going to find a roommate to take over my half of the lease. Our landlord was cc'd on her emails to me and didn't respond.

My roommate has since relapsed into a hypomanic state. We're joint-tennants on the lease. I'm worried that if she continues to live there and only pay half the rent, I could be liable for the other half. However, I don't have money to pay for two apartments. I can try to have my roommate's father physically move her out of the apartment and help find a new tenant. I can also show that I already found 10 good roommate candidates to fill my place.

What are my options? If I'm brought to small claims court, what can I be considered responsible for (we still have 18 months left on a 2 year lease)? How will this affect my credit? My landlord doesn't have my social security number or any other info except my name, so will that help me?

You need to read the lease. In most cases, a leasee is held jointly or severally responsible for the lease. This means that either of you can be held responsible for the whole rent.

And yes, the landlord does not have to let you out of the lease. And, if he takes you to court, you will lose. Your only help is that the landlord generally has to make a good faith effort to find a replacement tenant. Once he accepts someone your obligation for the rent will end.

Yes you have nothing in writing, no email, no letter, not even a note. They are not obligated to let you out of the lease.

And yes if it goes to court you most likely will lose. If you have a record of police reports where you called police on friend, if perhaps her parents will testify of how bad it was.

I have emails from my roommate to my landlord where she says per their conversation, I am to move out of the apartment. I also have the our grad school offering to provide me with an emergency dorm because it is unsafe for me to be there considering her delusions. And I found new tenants for the apartment, but the landlord didn't respond to my emails where I asked him to meet with them. Does he still have a case??

That may be enough if the landlord takes you to court.