How do I tell my Mom about a BAD grade?

Well, i don´t know how it happend to me, i´m a B+ student, but i got an E. She almost bit my head off last year. It’s jut the fact i had only A in English. And now I got a E. IT’S THE NEW TEACHER!!! She’s so annoyng and boring and you can’t study with her in the classroom and she dosen’t have a CLUE! How do I tell my mom about my BAD grade?