I appreciate why you and other people are criticising your mother. But as as a mother, I know how strong the maternal instinct is and how protective it forces you to be. I say that we often don't like our children, their choices and the things they do. But you can't not love them. It's not an optional factor. When a mother stands by her child despite them committing some particularly heinous act, this is why it occurs.
Sorry you're in pain. All I want to do is try and explain how this feels.
I became an expert at hiding things due to a lengthy heroin addiction, including time in prison and psychiatric detention. My top tip (for females) is to split open a sanitary towel and put it in there. Sew it shut if possible. When searching, most people (any gender) seem to have an aversion to checking them..even clean ones. If that doesn't work (it sounds disgusting but needs must), a used one is a pretty safe bet.