My advice to the OP is just to explain your feelings to your friend
They're both he and she emotionally twisted buggers, talking is for mature people.
I know that a month ago he beat her and from her friends I know that he has done once or twice before.
Then its a crystal clear sign that she's not going to leave him anytime soon and definitely not for you, if he kicked her ass three times in a row and she's still considering what to do that means she'll stick around for quite a while.
I figure if nothing has changed by the beginning of september then I will just get the hell out of there.
No you wont, just as i recognize her type i recognize yours, whiny buggers who unable to get the girl they want keep bugging them and making a doormat out of themselves, my advice is have a bit of dignity and bail out.
I know that if 100% nothing will happen
Yeah something might happen, if she decides to leave him one day and she still keeps you around she might actually be your "girlfriend" untill she finds someone she really fancies and dumps you without a word because she doesnt give a shyt about you as a man, she cares about you as someone who keeps her afloat when she has trouble but otherwise is useless to her.
And since she's a woman and you act like you have no balls she will be suprised at your reaction (when she dumps you or just breaks off friendly contacts) because you never acted like you had dignity in the first place.
And thats the absolutely best case scenario for you.