It hurts a lot. I know the feeling all too well. And you should change your locks. Although she can still find a way in if desperate. It’s like an obsession addicts have to steal (selling the iPad was a form of stealing just like using the phone money). They fear they won’t be able to get drugs or alcohol so they are always looking for an opportunity. I wrote about shopping with my daughter and I was paying for anything she wanted and she still stole the contents of a package of cold tablets and put the empty box back on the shelf. I asked her why she would do such a thing, I was paying for everything. She said she was sorry but this is something she’s used to doing and it came naturally. No one was watching! I’m sorry for you, your son, and the girl. I hope she’s able to get help.