Thinking too much about. Appreciated.

Thoughts, when they are intentional can increase our efficiency however automatic thoughts or rumination which is hard to control, works adversely. When it affects the sleep, it affects the natural functioning of the body and negative emotions start to overpower the body's natural instincts. This is a negative loop which feeds each other and might lead to depression. Suicidal thoughts are the further expression of helplessness. Now, there certainly is a way out. You can consult a psychiatrist and opt for medicine/therapy or a psychologist and start with therapy. In therapy, you would be helped to understand your thought and emotion cycle, work on it and master it so that you make your life much better than what it was before the unnecessary thoughts began. As you also have suicidal thoughts, i strongly recommond to consult a professional ASAP. Take Care.