Questionable motives

So we invited a friend and her boyfriend to come live with us.

She moved in and started paying small rent per room (basically covering extra expenses I'd incur, such as double the water bill and a lot more in electric).

This was several months ago (about 5 months).

We never had a lease, she paid rent in cash most of the time, paypal once, and this last rent she couldn't afford so her boyfriend (now ex) paid via check and paid for her room rent.

She started getting on our nerves. She would make a mess and leave it, she brought TONS of animals with her, which we allowed, but then neglected them, and let them stink.

She left everything for us to clean--dishes, utensils. We were actually to the point where we had no utensils because she took them all in her room and wouldn't bring them back down stairs.

Used all the paper towels and tolite paper without even contributing, etc.

She ate our food, took things that didn't belong to her, etc.

Put dead animals in my freezer (she likes to keep and sell dead animals)

We started getting sick of having to tell her NO over and over and over for common sense things.

We wrote up a list of rules for her to follow. She acknowledged reading them.
That was a couple months ago.

She continued to bring animals in after we told her not to without asking.

And then the kicker, the rules was no guests. She wanted to bring strange guys into our home after her bf and her broke up, at 3am and have them hang out. We told her possibly she can hang out with them on the porch.

she snuck them in anyway, and when my boyfriend found out, and told her to get him out, she told him NO.

So he gave her 30 days notice.

Her ex boyfriend is staying, he's become a good friend of mine, and he says she will try something to be vindictive.

NOW SHE'S TEXTING MY BOYFRIEND AND ASKING FOR A RECEIPT OF EVERY MONTH OF RENT THAT WAS PAID.

ANY CLUE WHAT SHE MAY BE TRYING TO DO?

It sounds like she's trying to pull something and I just don't know what.