How do you love someone who is not in step with reality and is blaming others for their problems? The obvious, but hard answer is to tell them. This is hard, though, when folks are living in insanity. It's hard to muster up the energy to be honest with someone who isn't living in reality. Personally, I find it hard to speak one truth to someone, when I feel like there's 100 things I need to say. The volume of things in my head freezes me a little.
But, results are not our business. Truth telling is as much for our peace of mind and well-being as it is to "help" the other person. One of my favorite phrases in the bible is when Paul says "as much as it depends on you, live peaceably with all men". "As much as it depends on you" is a freeing phrase that should give us courage to say what needs to be said, regardless of the mental state of the receiver.