"This is a man who was SO helpful when she was bedridden for nineteen weeks whilst carrying the boys. I know he has been depressed for several years, but has always refused seeking help."

1. He's depressed.

2. His personality has changed markedly.

Time to figure out what's wrong with him. He may never accept help, but knowing what's wrong will help your family deal with his crazy behavior and attitudes.

Second thought - if they guy is mentally ill, are the boys safe with him?