Roommates: Roommate Threatening to Sue

My question involves a roommate in the State of: Wisconsin

I recently decided to go apartment hunting with 2 other girls. We found a nice 3 bedroom apartment and split a down payment to hold the room. I needed to get final details for breaking my current lease and advised my friends of when that meeting was. The day before my meeting, one of the girls signed the new lease. I found out the following day that the cost to break my lease would be too much for me to handle alone and that there was a very low chance of getting a new tenant to take my current apartment by the move out date (making me responsible for rent on 2 places at the same time until a new tenant was found--no sublet option). The potential roommate who signed the new lease has threatened to sue me for 1/3 of the rent if I don't sign. Does she have a right to do this and will it be a valid legal argument? I have not signed any legal contracts binding me to the new apartment and the move-in date isn't for another 2 months.