Sadly one cannot help anyone, no matter how much we may wish to do so if they're not helping themselves. It's impossible. The inevitable is already in motion and you had nothing to do with it. My advice is that you do what you can, give him a reality kick in the head, but for your mental health, I would strongly suggest you seek a counsellor not only to deal with the present but also the seemingly inevitable.You most certainly should not suffer in guilt or shame. See a counsellor. My best wishes for you both.