I understand that guilt is a very natural emotion and though in your situation I would experience none whatsoever, I appreciate that you have cared for this man and do not wish him to come to harm. But ultimately each of us lives our life alone. We make our own choices and it is up to each of us to take responsibility for the choices we make. Sometimes we have to step back and let people make their own choices, even when those choices are not the right ones.
I sound harsh, I know but I urge you to live your life for you and let this man stand or fall by his own hand.