AstroPenguin

I completely agree with Selecttext as well as all the other posts above me. If just the wait and the uncertain future are causing you this much stress and anxiety, is it really the best thing to go into Grad School which requires a whole bunch of uncertain chaos? Also, you need to go to a counselor/therapist ASAP. Once again, if this wait is driving you insane and causing these emotions then (to be straight forward) you most likely are not mentally ready to handle Grad School. However, if you talk to a counselor and/or a therapist they will work with you in developing techniques to handle stress (and get rid of those thoughts...). In short, you need to manage your stress NOW before heading off to Grad School. Taking care of yourself should be your first priority (if you are happy, you will be more efficient with work).
 
There are some horrible events that have happened due to stress, for example - http://www.nytimes.com/1998/11/29/magazine/lethal-chemistry-at-harvard.html?pagewanted=all&src=pm
 
Plus, there are always options. Take a year off school and work (save up money). Take other Undergrad classes. Find a job. Also, look at this article (geared towards Phys/Astro...but still helpful), it lists other options if Grad Schools are in your near future - http://astrobites.com/2012/12/10/when-graduate-school-isnt-in-the-immediate-future/. Plus, depending on what you do, it could be a stepping stone into Graduate School next year. 
 
By no means is Grad School the only option though, it might seem like it...but its not.

My friends and I have long had the odd hobby of taking popular songs and changing their lyrics so they are applicable to whatever we are doing right now. I thought you all might appreciate my current attempt, and if you have 20 minutes, you should contribute your own.
 
 
To the tune of  "So This Is Christmas" by John Lennon:
 
And so this is waiting?
And what have I done?
Another day over
And a new one just begun
 
And so this is waiting
Its not any fun
My inbox still empty
My phone hasn't rung
 
I feel like I'm in limbo
I just want it to end
Just send my rejections
So I don't have to pretend
 
And so I'll be waiting
My heard filled with dread
Stalking result search
And the grad cafe threads
 
Its very scary waiting
I'm wringing my hands
Can't wait till its over
And I can make plans
 
Please accept me
I do want it
Please accept me
Nooooooow

Hi, I think a lot of people have said some very important things.  I just want to add something that I had written on another thread a while back. It seems appropriate.....
 
Self care is so very important under stressful conditions. Sometimes it is important to take a step back from the situation and gain some important perspective. You may get in, you may not. You may have to make some tough decisions in the next few weeks or you may not. But no matter what, there will not be a scenario that you CANT handle.
In the larger scheme of things, this is just one hurdle in your life and believe it or not, it will not be your biggest. It just feels like it because you are in the 'here and now'. If you look back at your life, consider all of your accomplishments. I'm willing to bet that you can think of several examples where you had to do something at least twice to get it right--whether it was learning to ride a bike or perfecting an academic achievement, it took time and patience to get it right.

You still have plenty of time to hear back from your schools. If you get in, that is wonderful. If you dont, it is not the end of the world.
If it helps, think about your plan 'B'. Although it sucks to get rejected, knowing that you can do something about it is empowering and motivating.
Most importantly, remember that getting into the perfect grad school does not define you as a person nor should it measure your sense of self worth. It is just one aspect of 'you'. If you get in, be proud because you have every right to be. If you dont get in, be persistent and know that you can and should reapply. And, be proud. This process is not for the faint of heart and getting this far says a lot about you as a person, regardless of the result.
 

I know the feeling. Last year, I was in the same situation, waiting endlessly for acceptance into anywhere. And the nerve-wracking wait just got worse when I knew that many of my friends were getting acceptances into their top choices or somewhere. In the end, it turned out I was rejected by all the programs that I applied to. I was so ashamed to tell this to my lab-mates, my advisors, my friends and everyone else who knew I applied for grad school. I had been through the shame, the self-doubts, the anger and the frustration but I didn't give up. I hold on to my goals and move on with my other plans. I tried again, and now I'm going to attend graduate school this fall, doing what I wanted to do.
 
I know this is tough for you but some truths remain. No matter how hard you think it's gonna be the end of your world if you got all rejections, it's not! Attending grad school THIS YEAR cannot be your life-determining event and your only plan. Whether you like it or not, there are so much more you can do before the next application season. You can always try again as long as your don't give up. And you are not alone! I believe there are many people on the forum, including myself, who have been through two or even more rounds of application before getting to where they wanted to be. Key is you have to realize that things don't always work out the way we wanted them to. 
 
Try to let go all the negative thoughts and move on while holding on to your dreams and goals. Things will always work-out eventually. And always get help if you need to. Good luck! =]