A few thoughts...
One I had something similar with a neighbor who had my number and texted me after I moved out of my unit and moved a tenant in to complain about my tenant and his dogs. I simply said the issue wasn't a lease item, but he was welcome to walk over and talk to my tenant...he never did. He asked for their number to text them which I declined since it isn't mine to give. The hurdle of discussing face to face was enough to prevent him doing anything for the remaining 9 months and then he moved.
In this case it sounds like she is really an issue, so I'd give her the happy clause. "It sounds like you're not happy with this living situation, so I'm willing to allow a one time lease break with no penalty so you can find somewhere you'll be happy". She will either leave solving your problem, or may very well stay because the reality is she just wants to complain. If she stays your response is "Great, well then since you are happy here I don't expect you to send any other texts like the ones on XXX and XXX". Now you have confirmation from her she's happy, and have set the expectation that she doesn't text you problems that don't exist.
If she's out of her lease time then the other thought is simply give her 30 days and re-rent. Even two weeks of turnover and cleaning will be worth the mental sanity that a stable good paying tenant will bring you. Screen well and you'll avoid a lot of these issues.