What should i do, stand back or try to help?

They need to try counseling, because something needs to happen. I don't know how your mother looks, but I think if she got a new haircut or lost some weight - it may bring back some of that lost pion. I really think your parents need counseling because your mother is worth it. Just because her husband thinks otherwise, it doesn't make it true. Best wishes. So yes, do something.