Hey, hey, don't panic. Sit back or lie down for a few minutes, and then use these remaining 3 or four hours as good as you can. And then this was the best you did and you have to see if those admission officers are convinced by it. You can do nothing to 100% ensure that they will take you, admission is a mixture of merit and luck (and who knows what else).

So after calming down a little bit, think about how to use the remaining time best. If your brother can't offer you help (or if he doesn't realize you have only limited time left, thus writing a new essay is not an option), then you must do without him.
If you still modify something, make sure you have ample time to read through it and see if everything fits together well. Check for typo's and that stuff.

Trust your own judgment. Read your essay out loud (as if you read to an audience). Imagine you hear it for the first time.

But most importantly, keep your senses together. Don't panic. and don't try to come up with too many changes in the last minute, the risk that you won't be able to finish it is too big.

and yes, they are supposed to teach you something in college, so college admissions college should not be expected to be at the level of college essays.

If you are still panicking, you should first calm down.

We have all been injured, profoundly. (Donna Haraway)
I Am Out, Therefore I Am. (Okay, mostly.)

Please don't be too hard on yourself. You're right - no college is going to expect a flawless, beautiful poem of an application essay. They look for potential. And I read your essay draft, and I definitely saw potential. They will too. Don't freak out. It was good. And just the fact that you had the guts to tackle a touchy subject like gay rights is going to make you stand out in their eyes - I think that essay will definitely work in your favor.

Switching gears:
One thing you said worries me:

"Why do I even try? Every time I think I have a chance or hope for anything someone has to harshly pull me down."

I think I know how you feel. I'm semi-shy and kinda sensitive - which I'm sort of getting the feeling that you are/were too, forgive me if I'm wrong - and sometimes I just get crushed by negative feedback that comes at exactly the wrong time, and start feeling horribly about myself. Please don't just accept everything people say. Don't let other people make you stop hoping or thinking you have a chance at something. Seriously. Screw them. What do they know. You know yourself best, just try to remember that if someone says something that makes you feel bad, or something you don't think is right, you have every right to completely ignore them.

Good luck with your essay, and don't be too hard on yourself.

Your essay had potential and that's what colleges look for, not perfection. There are also so many different things that schools take into consideration--as for extracurricular activities I wasn't involved with anything until my junior year and then I was only involved in Cookie club (don't ask) for most of it and it wasn't until the end of junior year and during senior year that I really got involved. Granted, unlike your brother, I may not be a college graduate, but I did get accepted to the college of my choice, and I know that they look at more than a persons current writing ability.

What about letters of recommendation? Work experience? and grades? And when it really comes down to it there are thousands of colleges in the U.S. and if you don't get into this one you will get into another one--one that you may find that you like even more.

Just try not to worry about it, senior year is stressful enough, and there's nothing more you can do about it now.

As for your brother, if all he can do is bitch at you then maybe he doesn't deserve to be asked to help. College level standards...you should see some of the shit I've read over for my peers.

People pay other people to write admissions essays for them, admissions officers know this, and that's why a lot of schools don't put as much emphasis on the essays as they used to.

What did I do my senior year to earn money? Let's just say I helped some people out....

Relax, try to stop thinking about it.

"So, when I'm an RA I'm going to tell everyone my name is Vagina, pronounced "vah-geena" and I'm going to write up the first bitch that gets it wrong."--Me