On the other hand you could be the unwilling part of the old "play one parent off against the other" game. Also brothers like to be together. Who knows - the old dad may spoil the heck out of them.
but anyway you look at it, this will be a tough one to win. Margypops may have the best advice. Second choice would be for both you and her to go for counseling (actually, now that I think about it, that might be a very workable idea). About the only other choice is to call their bluff (so to speak) and move out. Will they move back in? Its really tough on you, but it will at least give a hint as to what is going on.
I do have a problem with "it is all your fault" when you have been with them for literally all their lives. Good Luck!
Speak to her /them tell them what you have said here, make it from the heart, tell them you will change ,no more cursing of anyone!! You can correct this if you really want to change ,children dont deserve to be abused verbally or physically , if yiou cant do it by your slef go and get counselling .then ask them back, You can do it...