How to handle a rebellious teenager?

I know it happens to parents but I never thought my little girl would become so rebellious. She is such a sweetheart but lately she's been going to her friends house while i'm at work without asking, starting fights with me when I ask her to do chores or simple tasks, saying she hates me, and she won't talk with me about anything. She would rather stay in her room during dinner and not eat at all to avoid chats with me I think. What did I do wrong? I've always told her I loved her, i've always been open with her, and all I ask for is respect and good grades. It seems like right after turning thirteen she started acting this way. Is this normal? I am very stressed with financial issues and some problems with my husband. I'm trying my best not to show my weakness to my daughter.