Ugh... I didn't even realize it was time to almost time to pay property taxes again
I had a similar problem except I was renting my whole house to a friend and his girlfriend (expecting baby) when I moved to Alaska for a while... My mortgage isn't much compared to others, it's an old house, little small by some people's standards... The deal was they were to pay $675 a month, electric and gas bill, and I would pay for sewer, trash (because I wanted to be sure trash was thrown away, and not stacked up somewhere), and internet (because I still had a 2 year contract, and didn't want to pay the cancellation fee)... I wasn't trying to make money off of them, I just wanted enough to pay the mortgage while I was gone.
First two months went ok, third month the check bounced... At that point they had literally just had their baby, so I figured times were tough, and they probably had to buy a bunch of last minute stuff they didn't think of. We have a nice chat, told him I undsterand you just had a baby, but if you can't pay it tell me don't just give me a bad check. He gets me the money and the NSF fee I was charged for the bounced check the next week.
Things went fine again for another 3-4 months, I flew down to visit family and hang out for a while. I went by the house while I was down there to collect rent, and the "mother in law" is there and there is a giant stack of $#!7 next to the house... Concerned about the state of the yard, I asked if they were getting ready for a yard sale or something? The lady says, "Something like that"... Hmmm... ok. Couple months go by yard is still an absolute mess and it's starting to rain, I ask dude if they need a bigger trash can, and reiterate the reason I pay for trash is so shit doesn't end up in the yard and ask him to clean it up.
Well little did I know was that stack of crap was from the mother's house, and that her, her 3 kids were moving in, and with 3 dogs no less (No pets allowed)... Went to get rent again, ask dude about the vicious dog in the yard. He says it's the mom's dog, and they have to keep it for a while... Ok dude, get it out of here ASAP, I don't want to be responsible for it attacking someone, DO NOT let it in the house.
I head back to alaska, 3 dogs are still there, and there are 7 people (4 of which I didn't know about) are living in the 1100 sq ft house... Couple months after I got back to AK, there was no attempt to make the rent payment, let it slide for a while seeing if dude is gonna call, or what... He calls a month later, "Hey I got rent,"... To which I reply, "Ok, what about last months rent?" He doesn't know what I'm talking about and insists he paid it... "Well I didn't get it"... We go round and round for a while... rent starts getting paid again...
At this point, I'm packing my crap up in AK to move back to OR... Get back and dude brings me rent at the shop. I ask how many people are living there, and why the dogs are still there.. Turns out the mom, 3 kids, and 3 dogs are temporarily living there, should be gone by the end of the month... OK, DO NOT let the dogs in the house.
At this point, I'm living in my Dad's guest house paying him $500/mo... I could be living in my house for a few hundred more. Couple months go by, still a full house, get another rent check with NSF... It's about last Thanksgiving, I finally pull the plug, but being the holiday season I didn't want them to have to worry about moving during Christmas, so I tell them they need to be out by the end of Jan.
No problems with the rent until they leave... Finaly get the house back it's a mess, all the carpets had to be replaced because they obviously let al the dogs in the house... So I start project JacFab Extreme Home Make over, it took me a month of replacing carpets, painting rooms, refinishing floors, and cleaning their junk out before I could even move back in... The deposit they gave me was barely enough to cover the materials to replace the carpet.
There's more to the story, but I think you get the idea... I never did get the missing months rent out of them, and it cost me about a grand to get the house livable again... Maybe I should have been harder on them, but you can't squeeze blood from a turnip. I will NEVER rent to a friend again.
*EDIT* I realize that basically doesn't answer your question of what you should do... I still consider my previous tenent a "friend", but we don't hang out or talk anymore. I have never asked for money for the missing rent, or compensation for the damages, no do I plan to... If your friend doesn't get her act together, I would simply ask her to leave as it's not working for you.