I can't trust my mother.
That's strange. Why wouldn't you trust your own mother?
My mother hasn't been loyal enough to me.
If you genuinely feel this is an issue between you and your mom, you should talk about it with her.  When you have serious doubts like this concerning a family member, you want to resolve the issue rather than just ignoring it.
But it's just going to make her mad. Fine. I'm going to bring it up tomorrow and see how she responds.
I hope it works out. Just be calm when you talk to her and explain to her how you feel and that doubts you have. It should help you resolve your issues and help your relationship with your mother.