1. Eating 1600 calories today is NOT a problem. Remember that's only just over your BMR. It still puts you in a deficit. Relax, for goodness sake.
2. New and unexpected sources of stress in your life do NOT, I repeat, do NOT give you leave to countenance thoughts of hurting yourself, severely restricting, or trying to make yourself sick. None of these things will solve your problems. They will only make them worse.
3. Smile. You're nearly through these exams and you're doing fine. You will find somewhere to live next year too.
4. Go swimming tomorrow. It will make you feel better.
5. Get some sleep. Wake up early, eat breakfast, and study for your exam.
6. You can do this. You have come so far from the girl you were, but you can go much much further. Just keep going. Girl, you got this.