Why did my mom lie? AND betray me?

My mom and i have always Ben ultra close,but today i found out she lied to me twice. I told her specifically not to tell anyone my secret and she went and told someone. When i found out...i asked her and she looked me straight in the eyes and denied it. She lied once again. What hurts worse... the lie? or the betrayal ? I don't know if i can trust her again. I love her with all my heart and shes all i have...or thought i had