Dear Glimmer
I hope that you are doing well, and I am sorry to hear that you are having difficulties with your husband of 40 years.
Please, don't stress too much about your relationship with your husband - I know this is easier said than done. 40 years is a long time to have been together, so I can only begin to imagine how you must be feeling at the moment
One of the first things you will need to do, Glimmer, is get a support group together. What I mean by this is a network of friends and family who you can call upon in times of need - when you are feeling down in the dumps or just need someone to talk to. This is quite important. Having been with your husband for 40 years, you may have come to depend on him for some sort of emotional support - maybe without even realising it. Knowing that you have friends and family that you can call upon will help keep your mind at ease and keep those stress levels down
Another piece of advice, which once again is easier said than done, is try not to blame yourself for your husband leaving. He is big enough and ugly enough to look after himself and to make his own decisions (excuse the term). Sometimes, people just need time apart in order to realise what they have got. However, don't let him string you along. You are a kind, caring person who has feelings and you deserve the best the life has to offer you. If he starts with the mind games, don't respond. I have found that men often try and play mind games with women in order to try and win the "power game"

(When will they learn - women can always win if we can be bothered with playing them, the only times men really win the "power game" is when the women just can't be bothered with it all - LOL!).
Glimmer, I don't really know what else to say without knowing your situation. If you find that things start to get stressful, and that you start to feel down in the dumps because of it all, please, let me know. I have some very useful exercises that can help with depression and the like (I am thinking of starting a pyschology course this year

).
Wishing you all the best and hoping to hear from you soon
Auss