Like the others have said....ingore the cheating ex. You need positive, supportive people around you now more than ever!
Tackle each task one at a time. Make a goal to have one chapter read by a certain time and so on. Sounds silly, but it really helps you not feel so overwhelmed when you have a stack of work if you just think of it in bits.
When you have time, don't forget a little you time. Even if it's a nice long bath. If you feel too guilty, you can always study in the bath tub, that's what I do.
After the test, good or bad, take a breather. I always grab a latte and wander around our local antique mall. Sounds corny, but it really helps clear my head.
Good luck and remember you CAN do it.