Preach. As D was talking, I’m wondering why MM isn’t stopping her and being like...you had those kids, you chose to invite some stranger into your home with 3 kids! She would follow up with some stuff that tells me she’s not being honest - I stay with my mom sometimes to spend the night with the kids (I thought the reason you had to have a roommate was the 3 kids that lived there), then ‘I called the cops about a window but...oops, the door was unlocked.” (You seriously didn’t try the doorknob before calling the cops about a window you didn’t really know was open or not?).
If you’re inviting a nutty stranger into your house, you don’t get to complain about needing to safeguard your stuff (put a better lock on the door). I also don’t think you can say the lunatic canNOT have a lock on hers. I have an idea...get a smaller apartment that you can afford.