I think that I would have forwarded it to him, with a short "look what just arrived in my inbox-..." I dont know if you should call him, I would probably text him, just tell him that she contacted you, but I dont know how to bring it up... Boy, Im not sure. Maybe you could return his call now, but not bring this most recent thing up, just to test the waters...
If you tried to tell him about it, how would he react, would he defend her?
I guess I gave the wrong finger to the wrong man...