.- The other two tenants really appreciate everything I have done and are willing to help out in whichever way they can (whether it is acting as a witness in court or preventing her from doing more harm).I understand that in Massachusetts I can do very little as a landlord against being abused this way, but if there is anything myself or my other tenants can do I'd love to know.

If they don't like it for any reason within the 7 days, then they can get out of the deal no harm no foul, and their money will be refunded to them.

Bipolars are not violent though they do have a tendency to self harm.

So in that regard it would do more help than harm.

yes indeed, I was actually taking a class online and it was on human relations in the workplace, and I would laugh when I came to work, because I would watch things happen right before my eyes that I was reading about the night before.

Short selling it or walking away from it will do her more harm than good and probably unnecessary.How much rent is she getting on it?

Not sure what state you're in and what is allowed; however if you let him do the work, and there's no problems with the installation, no harm no foul.

We don’t know any PMCs to recommend in the area mentioned, but since selecting the wrong PMC is usually more harmful than selecting a bad tenant, you might want to read our series about “How to Screen a PMC Better than a Tenant”:https://www.biggerpockets.com/member-blogs/3094/91877-how-to-screen-a-pmc-better-than-a-tenant-part-1-services-and-processesWe recommend you get management contracts from several PMCs and compare the services they cover and, more importantly, what they each DO NOT cover.

There is no harm done in expanding your mind.

I would split it or prorate it and tell her that you are a good guy for doing it and not keeping the whole amount. that she caused you harm by you taking her by her word.