Hi maggie,
You're up late, or are you in a different time zone, like me?
I suspect you are just up really late worrying, so I am posting you a reply to let you know that there is someone here.
I'm afraid I cannot offer you any good advice, but have read the other replies and agree with them.
Forty years of marriage is remarkable, that's why I feel intimidated to reply to someone as big as you.
I strongly suspect your husband has met someone else, or has feelings for someone (no doubt much younger than him, hence the insecurity on his part). At the moment he is 'covering his options'.... a bit of a 'let's see if it's going anywhere, before I jump in too deep and lose everything'.
My opinion, for what it's worth, would be to get straight to a solicitor and find out what your financial circumstances would be. Also, I think you should be totally mercenary and 'take him for all you can'.
Then tell him what he stands to lose, quite a sobering thought for a middle aged man behaving like a teenager. Also, it may effect the decision of the person he is (maybe) seeing.
Quite frankly, just make his life so uncomfortable that he maybe will come to his senses. If he doesn't then you know you never stood a chance anyway.
I know lots of men that have boats, and often escape to them despite having comfy homes.... it's just the up-market version of the potting shed.... or if you have ever read the Venus and Mars books, their caves.
However, seeing the pain and hurt you are suffering (whilst waiting for him to 'grow up'), I have no sympathy for him whatsoever.
Dress up for your daughter's wedding, as if your life depended on it! Plaster a brave face on and enjoy the day despite him.
I really hope things work out for you.
Big hug.