i did change host family too. It's not that difficult if you have enough reasonable reasons.
did you talk to AFS? i think you need to talk to ur liaison first then AFS and liaison probably come to your house and discuss about the problems (or may be not, it depends)
Why would you care if your host will hate you or not cuz you'll change host anyway.
Changing host family doesn't mean that you will get the better one. The new host might be worse. So let's take time and think about it that you "really need" to change host family or not. (why you dont want to stay there, it is their false or yours or not anyone's and is there any solution.., have you done your best (i mean have you tried to adapt your self to fit in with this family and solve the problems) and etc..)
and yes you might need to change school as well, so you have to make a good decision.
Good Luck. : )
70 percents of AFS students change host family too. so don't worry. : D