It would depend on local legislation.
I hope you have a copy of the original lease agreement. What she did is not legal.
You must be 18 years old to enter into a residential lease agreement in the USA.
Electronic Signature
check on the lease agreement but often you can find replacement roommates to take over your lease
If the age of consent into a legal agreement is above 17 then no lease has any legal standing. Therefore it does not exist, legally.
This is a legal question for which you must consult an attorney. A standard lease agreement may be available at your local office supply store.
kentucky
Giving your electronic signature is legally binding, just as is your real signature. However, the website should have a statement of some kind warning you of this, and getting your consent (given or implied) that your electronic signature will be used as such.
An agreement does not get notarized. A signature does. Most contracts do not need notarized signatures to be binding.
There is no legal route to get out of a typical 12 month lease agreement (I assume this is what you are referring too). The best way is to explain your situation to the landlord of why you feel you need to get out of the lease agreement and see if they show any sympathy and let you out.
All parties involved must be over the age of 18, and must have attached to rental lease agreement all necessary state disclosures.
Is it "legal"? Sure it is. There are complications if you have a lease agreement, but that's civil, not criminal.