@Robert Stack This comment is meant to protect you and help you before you find yourself in a worse situation, which you probably will from what you posted.
You should turn this over to professional management now!
You clearly know or have an idea of what you should be doing, or so you claim with the “I researched tenant/landlord relations extensively” comment but have failed to implement even the most basic processes.
Such as do I want to be in a month to month with this tenant or speak with her about signing an annual lease prior to and the day you take possession of the property?
Why didn’t you see/review the month to month lease for this tenant?
Why did you not do anything for 2 months? You probably wouldn’t have done anything if this issue had not come up.
You keep saying you know this, you should have done that, that you’re a pushover, and on and on.
Take appropriate action, set ground rules, wait... before that actually figure out what your ground rules are, then get your tenant to sign some kind of lease that was vetted by any competent person (lawyer/investor/broker/agent) and start implementing all the great advice you have supposedly learned/read.
If you can’t do that , then hire a property Mgmt co. and be done with it.