I Have Panic Attacks

I remember when i was younger, i was hearing my dad screaming to my mom and i was so scared. Since then, i have panic attacks. The last summer my dad hit my mom. And i was in front. I had a panic attack then, i was crying and i couldn't breath. My parents are ok now but i just can't forget it. Every night that i go to sleep i remember what happened and i cry. I don't know what to do. I feel so sad and alone. I want my parents to be happy, i love my dad and mom but i just can't forget the times when they were fighting and when my dad hit her. Sometimes i think i'm going crazy. I'm 14 and i don't want this to ruin my life. I like maths but my teacher on school thinks i don't know anything. I'm really shy and i can't talk very loud. I don't know what to do. Please i want to talk with someone, just talk or give me your advice. All my friends on school are girls who have a nice family and are always happy and rich and i can't tell the anything. I don't want to have panic attacks no more, i want to be happy and forget what happen that summer. But i can't. Please help me.