Husband so sad.. abandoned by best friend. How do I comfort him?

First, if he's a friend your husband should focus on what is good for his friend, after all isn't that what good friends do?

He might try looking at the positive aspects, like maybe this is what his friend needs, not that his friend is abandoning him. We should not live our lives for other people, it isn't right to want to hold those we love and care about back, just because we will miss them, that's just plain old ordinary selfish.

Comfort him by telling him the truth, don't coddle him, it sounds to me like he's had enough coddling. Being honest, explaining things like you would to an adult, in a way that makes logical sense might work if how you have described your husband is true. He should be able to respect a logical argument.

Also, maybe this is your time to step up and be your husbands best friend. Be the wife you are suppose to be, which should include being his best friend among other things. If his best friend is someone else other than you, that might be indicative of a totally different problem. You will have more time with your husband to explore all those things friends should be exploring.

Trying to keep people you love close to you because for selfish reasons is wrong. Wanting them to make decisions in regards to their life so that their life revolves around yours is selfish. Being sad they are leaving is only natural, but if you focus on what it means for them instead of what it means for yourself you might find that you are happy for them and it could change your entire perspective.

And whatever you do, don't make the friend out to be a bad friend, or wrong for wanting to leave what reminds them of their ex-wife. Be supportive of his decision, make it easy for him to stay in contact and/or come back after he has sorted his own problems out. If your husband is not careful it might not be that his friend is leaving for good, it might be that he stays away for good because of how he was treated before he left.