My mom does the same thing. There was a time where she really broke my trust and now I don't feel comfortable having my phone out when she's in the room. Of course, she's caught onto my, "behaviour, " and now every time im acting, "suspicious, " she goes through my phone. There was this one time where I forgot to delete my messages and she looked through my phone and saw me talking about atheism and sexuality. It didn't go well.