Sorry to hear about all that, Casablanca.
Is this guy actually blaming you in some way (for his disappearance)? Is he saying he just had to have your wife all to himself? Either way, I agree with you, that was pretty rotten of him.
Don't beat yourself up over this, it seems clear to me that you've done everything reasonable to help and then some.
Even if you feel there's not much more to be accomplished by frequenting Polyamory.com, I just want you to know that (as far as I am concerned) you are always welcome here. As it is, I appreciate that you shared your story, as it will help others in the same boat know that they're not alone.
Love means never having to say, "Put down that meat cleaver!"