Let her and counter sue for the rent.

Don't stress about it. let them sue, don't counter sue and waste your money. I think they are just empty threats they don't have the money to sue and anyway they are responsible for the bill.

There are a few factors going here. She can TRY to sue but the bill is in her name and if there was no written agreement between the two of you she probably won't get anywhere. I'm assuming you are talking about a utility bill? A judge will take that into consideration however, because you used the utilities also. Since she broke the lease you could get at least one month's rent from her. Under the law you would have to try to find another roomate, so a jodge would not give you the full term of the lease. Depending on this bill she's talking about, you should think about how it balances out. Let her know that she owes money also. If you get a summons, make sure you countersue. You should then say that you tried to "mediate" with her to settle before it went to court. A judge might take this into consideration also and rule completely in your favor. This is what happens when roomates sign a lease together. The landlord can choose to go after either one or the other and since you are still living there at this time, you are responsible. If you move out also, the landlord would have to sue BOTH of you, but that would go against your credit and harm your references. You didn't mention how much time is left on the lease, but you either have to try to find a new roomate or ask the landlord to let you out of the lease. The landlord might do this if he or she is a decent person. Otherwise, you're stuck to the end of the lease.