Confront him. But hold your temper. He has been dishonest with you telling you they are just friends and writing this love sick stuff to her. Your husband is acting childish. I would definitely contact either the presenting couple you related best to at the weekend or the post session leaders and discuss these events. Your husband is leading a double life. This is unacceptable but you must not fly off in all directions. Get help from the people you trust. You need a Retrouvaille husband to talk to him.