Honey, the others are right. In the first place, you really shouldn't have looked at those things, because that package was for your Mom. She would be VERY angry if she knew that you snooped in her mail. You really shouldn't have done that. But that's over and done with.
Does your Mom hit you alot? When she loses her temper, do you get hit or slapped alot? Does your Dad know about it?
Please talk to a counselor at school and see what he/she has to say. I'm sure they'll be able to help you. They can at least tell you what the next right thing to do is.
I wish you the very best, honey. PLEASE let us know what happens, will you? And know that we're on your side, and you can talk to us any time you want to or need to, okay? God bless and please take care. Hugs, Lee