You can sue the other roommate for the share not paid. If the other person has assets you may collect something. If not, you will likely spend more money, that apparently you dont have, and still not have anything to show for it. Sounds like you need to get a new roommate who can share the expenses and will pay them up front.
The answers given are limited to the facts as given and presumed by the answer itself. Without seeing actual written documentation or having a conference to more fully explore the issues, this short answer has only limited application. Make sure to seek legal counsel and provide all documentation to get assistance in making informed legal choices. Bstein@dcfsz.com, 305 377 1505
Consult a real estate attorney. If the 2 year lease is not signed by the landlord and two witnesses you may be able to get out of the lease. You may email a copy of the lease to me for review at firstname.lastname@example.org
I provide a free 15 minute telephone consult for security deposit claims and eviction defense. No attorney-client relationship is created by answering questions in this public forum. If you wish to create an attorney-client relationship, you must contact me directly and sign a representation agreement. Answers are provided based on general ideas and an answer specific to your situation would require a review of all documents.