Fired A "business Owner" And Now She's Coming After Me

Fired a handshaken "business owner" and she's coming for me

I started a business 2.5 years ago with a friend, Julia. We acted as business owners, though she never invested into the company. Since she didn't, we put only my name on the business accounts and government documents. Her name was not listed on the incorporation at all, there was no shareholder agreement written, no made document stating she is half owner or anything. Her email signature had co-founder in it, and her social media posts for the company had the same. I guess it was more of a handshake deal. She had access to the bank accounts, and was acting salesman for the company.

Recently, she forged my signature on a document to change the company name which she also signed herself.

I ended up "firing" her, after a huge amount of drama where she was screaming at me infront of other contractors and my family. I then changed the passwords to everything and told her we were done.

Julia has sent me a demand letter through a lawyer and states what I have done is illegal. But she is not on the business name, has nothing invested, no shares.

So my question is, does she have a leg to stand on in court? Is a handshake deal enough to make you a business owner If it is, is she liable for some of the debt we've accrued then?