The simple answer to your question is “no”. It’s not normal to live in such a chaotic family. You all need serious help. Your dad apparently has a diagnosis but isn’t being adequately treated for it. Your brother is modeling after your dad (who is his role model for how a man should behave). That makes his meanness make sense but it doesn’t make it okay. It sounds like your mom is at the end of her rope so she is turning to her daughter for support. That’s understandable but it isn’t helpful. She needs to be doing what she can to get your dad into treatment and to get adult support for herself.
You didn’t mention why you have moved so much. That does make things much, much harder since your mother and you probably have difficulty maintaining the kind of friendships that can provide support. It may also be one reason that your dad hasn’t received the consistent treatment he needs.
By the way: It’s not at all unusual for a kid who has a difficult family and who moves a lot to read books a great deal and to think about fictional characters. It’s an important way to cope. Both books and movies can transport you to a better world for awhile.
Your whole family needs some therapy. Your dad needs treatment. Your mom needs to be talking to a therapist, not her daughter. You and your brother deserve a more stable home. Family therapy coupled with psychiatric treatment for your dad would help a great deal.
I hope you will talk to your mom about getting the family into therapy. You can’t be her therapist. It is unfair for her to ask you to be. You need her to be your mom. If your mom refuses, then do what you can to get some support for yourself. Talk to your school counselor about how to get connected with a therapist who specializes in work with teens.
In the meantime, if you need to talk to someone, do consider calling the hotline at BoysTown. Don’t be be put off by the name. They talk to girls, too. Counselors are available 24/7 to talk to teens who are struggling. It is anonymous, free and confidential. The phone number is 1 800 448 3000. There is also an option for texting. Check out the website: http://www.boystown.org/.
One more thing: You will be able to leave home in a couple of years — but only if you start planning now. Work hard in school to get the grades you need to apply for scholarships to college. Get a part time job. Be thoughtful about learning the skills you will need to get a good job after graduation so you can move out if you don’t go on to college. Save your money so you will have what you need to get an apartment and maybe a car. Set some specific goals for yourself. Working on them will help you stay out of the house and focused on your own future instead of on the family mess.
I wish you well.