I've Been Screwed Over. Can I Sue

Are you and the ex still on good terms?  I think you could win because she did sign the contract which left you responsible for the amount she didnt pay.  To make it a sure thing I would bring the ex.  SInce the contract is between the ex and the "friend" the judge might want to speak with the ex.

Good Luck and Happy Holidays! 

I have to agree with SpecialK. Definitely bring your ex to court. That way there is no confusion or 'he said she said' going on when you do get to court. In this way, you make your case as strong as possible in court.

As you were not a direct party to the contract, it is hard to say for sure. The small claims courts in most states provide free assistance.

Also, you may ask a local attorney. Most will NOT charge for a first visit.

Here are some great city-specific legal directories to help you find one:

http://www.san-francisco-oakland-bay-area-lawyers-attorneys-directory.com

http://www.sacramento-ca-lawyers-attorneys-directory.com/sacramento-legal-services.htm

http://www.la-orange-county-lawyers-attorney-directory.com/los_angeles_orange-county-legal-services.htm

http://www.las-vegas-nevada-lawyer-attorney-legal-injury-defense-directory.com/las-vegas-lawyers-attorneys-legal-defense-services.htm

http://www.san-jose-ca-lawyers-attorneys-directory.com/san_jose-legal-services.htm

http://www.sacramento-ca-lawyers-attorneys-directory.com/sacramento-legal-services.htm

http://www.dallas-fort-worth-texas-lawyers-attorneys-directory.com/dallas-legal-services.htm

http://www.new-jersey-lawyers-directory.com

http://www.legal-advice-library.info

http://www.san-antonio-texas-lawyers-attorneys-directory.com/san_antonio-legal-services.htm

http://www.brokerforyou.com/san-diego-real-estate-sales.html

http://www.new-jersey-lawyers-directory.com/new-jersey-bankruptcy-law.htm

You write:

In September 2007 my ex-boyfriend and I broke up. My phone and the “friend”'s phone were then put in my name.

Who did that? Why? The "friend" has a phone and it's under your name? It doesn't make sense to me. Just remember before suing that you have to have a valid basis upon which to sue her. You must prove--

1) the "friend" breached a written or oral contract with you, or

2) committed a tortious act which caused you damage.

It's not clear to me from the facts given that you have a valid basis for suing her.  

This is likely over now ... but must add that there was another basis for her recovering eventhough she was not a direct party to the contract:  she might prevail as a "third party beneficiary" of the contract signed (in that it agreed to pay a bill which if not paid as agree fell on the questioner ... so she was a clear 3rd party beneficiary to that contract and as such would have standing and right to sue under it.