When jealousy gets to the third-degree stage, it's causing both of you a lot of pain and you need to seek outside help - professional help is the best.
Therapy will help you come to terms with your problems and realise the consequences of your jealousy, from the financial implications (private detectives, following his every move, and resorting to illegal procedures to spy on him) to the health implications (loss of sleep, suicidal tendencies, loss of appetite) to the final straw: losing him because he can't cope with your issues and hysteria any more.