I said something very mean about my dead dad
Why did you say mean things about your dad?
He's a total douche, he wanted me to fail always and I hate him
I'm sorry he was such a jerk to you, and I'm also sorry he has passed away. Generally we should treat our parents with respect, but there is always gray areas. You should try to make peace with what has happened in the past and make an effort to strengthen the positive relationships with those who are still in your life.
ok I'm writing another thing that's better.
Maybe you can write a letter to your dad and get some of your feelings out and help get some closure.