Job causing severe anaxiety

I am 24 years old.
I studied psychology and have my honours degree.
Until August last year I was doing something I really loved which basically was therapy for mentally ill children.
Unfortunately they only hired students (really bad pay) and due to management issues many of us ended up resigning.
It was a very difficult decision for me to make and admittedly I made the HUGE mistake of accepting the first offer I received which was in a COMPLETELY different field to which I studied. At the end of the day I had bills to pay.
I was hired as a recruitment consultant...and in the initial interviews they said that I would be applying my psychology degree as well as helping people and thats what hooked me.
In the beginning I enjoyed the fast paced atmosphere but slowly but surely I realised I was a round peg in a square hole.
Its only about sales, and I feel I lie to people than rather help them.
I miss making a difference and contributing to something greater than me.
And by November last year I realised I hated my job. I cried on my way to work and during work in the bathroom and on the way home.
What doesnt help is that I live alone so there isnt always opportunities to talk to people.
This situation has given me great anxiety. I constantly feel like crying and due to the stress I have become gravely ill. The doc said due to my stress and anxiety levels of returning back to work this year, my immune system took a blow and I have been in bed. I return to work on Friday.
I have an interview tomorrow which I am really excited for and I pray with all my might that its right for me (it is in the psychology field).
But until then, what can I do to relieve this feeling?
How will I get up on Friday morning and go to work and put a smile on my face?

Wind, I applaud your conscientiousness nature. Most of us anxious folks are so. At 24, I'm pretty sure your immune system will bounce back quickly. Are you sleeping OK?
To relieve this feeling you try a few things. (1) Aerobic exercise works wonders for me(stress reliever/mood brightener....big time). (2)You should understand that this is a temporary situation now that another opportunity has come about. Now I have a hunch you feel it will be hard to quit. Scre%w them! In this case it's OK to get a touch mad and just resign if/when you secure the other spot. Just give the minimum notice and tell them you found a wonderful opportunity. If they ask for details tell them you are not obligated to say and have been asked not too.
You need to go though with Friday and until you leave to keep your reference(I think). Will be good for the resume.
(3)Now, make lemonade out of lemons. The time you spent at the hideous job will give you a better perspective when you try to help others with job issues. They are a common issues and it kind of makes you a better psychologist having been through what you have compared to someone who just read about it in a book. (4)It will also give you a better appreciation for a good work environment.
Think about all this as you've been trained to get others to think about their issues. Sometimes there's something to be gained by suffering. I mean that. I have learned through my own suffering and now I can help others(try anyway) from what I've learned from my struggles and often we all do. But at the time we don't see it that way(it's where you are right now). Once we do it does make it easier.
Don't feel bad you're leaving you current spot. Don't even look back. Sounds like they used you like a piece of toilet paper. Look forward. Wipe your feet on the way out and learn from it all. You will get through and be better for it. I know that sounds stupid but there's allot of truth to it. Try to smile as you realize that you will actually be stronger and wiser for this experience. As strange as it sounds, it very likely will do just that in the long run. PM me any time. Alankay.