I hate my brother's girlfriend and my mom hates her and my other brother what do I do she is such a control freek and thinking that we are all stupid what do I do?

Some times the best thing to do is avoid as much as possible and don't get into debates or arguments any more than necessary.
Trying to convince your brother can backfire so I really would watch with any attempts at that.

I agree with above - just wait it out and try to avoid her.
Hopfully it won't get too serious between them

As Nohelp suggested, sometimes the more you fight about an issue, the more likely you are to drive them closer.

Are you in a position that you have to be around your bro's girlfriend often? Try your best to be the bigger person and be as pleasant as possible and you may find out she's not as bad as you initially thought.

Often you have to learn when not to do anything

Like the first one. Trying to convince him will not end up well and will backfire on you. How often do you see them? If you don't see them that often then you shouldn't worry that much about them. But if you seen them more that that, just try to stay out of the same room as her and try to keep your distance from her.