Hi!
So sorry you found yourself in this situation that most of us here are in!
I would suggest to take your last tablet on a Friday (if you still have some), so the worst of the withdrawals will be over the weekend. Generally speaking, the worst of the physical withdrawals takes about 72 hours (but can vary depending on your habit, size, etc). I am 5'4 and 115lbs and was at a 25 a day habit and it took about three days for the physical part of the withdrawals to subside. It will feel as if you have a horrible case of the flu- upset stomach, shakes/chills/sweats, aching, insomnia, runny nose/watering eyes, yawning....
You may use the Xanax for the first couple of days (as I did) and it will help with the shakes and nervousness, but be very careful as it is addictive as well. The trazodone is a sedating type drug and may help you sleep (although if you don't sleep, it won't be abnormal). You need to get some Immodium AD (for upset stomach), Benedryl (for runny nose/watering eyes and this may help you sleep, too), and Aleve or Motrin for the aching. Get some Epsom salt and take as many hot baths as you can and also stock up on Gatorade, soup, popsicles, etc. After the first two or three days have passed, get some L-Tyrosine (from Walmart) for help with energy and MAKE YOURSELF exercise in some form or fashion- this will help with the lethargy and depression that looms once the physical symptoms subside.
If you "started" the process on a Friday and get through the weekend, you may have to miss a couple of days of class but should be able to limp in by the middle of next week. Sleep will be the hardest and probably last thing to "work itself out," which will lead to feeling lethargic and unmotivated, but this will pass especially if you exercise!
Good luck- it is a hard thing to get through but noone has ever died from it and many have done on this board including myself once. You can do this- post here as much as you need to for support.
Take care and God bless,
Michelle