Can this be considered bullying by my father?

Wow...your Dad. Is there anyway you could move in with your brother and tell your Mother to get the hell out of that relationship? Their relationship isn't your chore to keep it's theirs and they are doing a horrible job at it, your not to blame. You sound like your doing well in school which is great, keep up the good/hard work. Soon you will be out on your own and life won't seem so hopeless, you are what matters, play it cool at home, avoid the **** but be cool and get outta school. Again, see if you can move in with your brother until you graduate or something. Because your right, you shouldn't have to live like this...it's mental cruelty. You need someone to talk to, is there a school counselor that you could talk too? I wish you the best in these horrible times but remember, they won't last forever so hang in there no matter what happens. Don't you dare give up on yourself.