If you are having suicidal thoughts, you need a mental health evaluation as soon as possible. Thyroid disease can worsen mental health issues, but would rarely cause them to suddenly occur - especially if your levels have been reasonably stable with medications.
You didn't say if you are being treated with thyroid meds.
Your suicidal thoughts might be stemmed from the stress that you are going through with your parents splitting up and up coming exams. Thyroid can play havoc with our mind or make existing mental issues worse or even come to the surface. But suicide, hopefully not! However, you should seek a doctors advice and help to find out where this all is coming from so you can be treated properly. Thyroid did a mental number on me in several different ways, but never did I think of suicide. You can't be treated over the internet so please get help from your doctor. Good Luck!
Thank you. Yes i am being treated for my thyroid. Carbimazole and thyroxine.