If the utilities bill is in my roommates name, can she legally force me to pay it?

They can't expect you to pay without showing you the bills. If they took you to court over them, they would have to provide the court with the bills which you would get a copy of when you're served. I'm sure her lawyer would tell her all this. But, yes, you can be compelled to pay, because I'm uming that the agreement when you moved in was that you would all split those bills equally.