It is her 18 (almost 19) yo daughter.
The daughter will not go to school , as in high school and has reached the point of being unable to finish and has been told to pursue her GED. She is not pursuing her GED , any kind of work , or anything other than partying , sleeping all day , rinse and repeat. I see no signs of any drug or alcohol use or problems. I feel it's just a failure to launch issue.
Now, I could be wrong, but most likely her 18 (almost 19) year old daughter is most likely doing drugs and drinking (not necessarily to the point of being a problem, mind you). This is an issue her mother needs to deal with, and you can be supportive of that.
As far as her making use of your house, you have every right to be angry. My own parents would not liet me live in their house after I graduated high school if I did not work to support myself. They also refused to pay for any of my luxuries like car insurance, cell phone bill, etc. I was also going to school full time, paid for on my own bill.
So, no, I wouldnt say you are out of line, but before you end what is an assumingly good relationship over this, you should have this convo with the girls mother.
). Thankfully, the soon-to-be-ex knew the entire situation was BS and she had the class to say so to the officers that responded to the daughters bogus claims.