How about working on some desensitisation exercises? Rather than just putting the dog in the crate and then leaving - insert some baby steps into that, so that the dog is relaxed and happy BEFORE he actually ever gets left. Dogs need to be trained to be in crates, after all
The best way to go about it now would probably be to start crating him for short periods during the day, when you're home and there with him. The crate should be located, btw, wherever the centre of activity of your house is - NOT tucked away in the bedroom on his own (that's fine at night, no good for this training purpose though).
Start small - just pop him into his crate with a kong or something else interesting to chew on - whilst you're sitting there watching TV or something (crate being in same room). Don't make it any big event, just all nice and casual. After 10 minutes or so, open the door and resume your seat watching the TV, but don't pay any attention to the dog (especially if he comes bounding out). If it's possible, wait until he's not begging to come out to let him out (don't want him to think that crying or barking or being upset is what causes you to open the door).
You could do this several times a night, always with a nice reward and something interesting for the dog to do in his crate (that he doesn't get out of it), and always calmly and matter-of-fact. Same when he's released, it's just all casual, no big deal. And don't call him out if it ever happens that he prefers to stay in a few more minutes with that kong or bone or whatever he was given in there!
What you're trying to work toward is the dog being perfectly happy and relaxed about being in his crate - not just at household shutdown for night time. When is IS reasonably happy, then start doing normal stuff like getting up and making yourself a cup of coffee - which you'll then calmly bring back and resume your seat to enjoy. Then a bit later (enough time to be unrelated), the dog is released. And so on. Work your way up to this being a normal part of the daily routine. It never has to be long periods - but should be variable (5 min, 20, 5, 10 - whatever suits and leaves the dog guessing).
THEN, when that's all going well and the dog is content enough to give most of his attention to his bone rather than you/where you are/when you're going to open the door - go to the next step and leave the house. You need only go and sit outside the door for 5 min. Then return, and resume your seat as though nothing's happened. A bit later, release the dog. And then do it all again an hour later. And so on. Once again, work your way up in duration (and keep varying that duration - you mustn't be predictable).
When you reach the point that the dog isn't paying too much attention, then you've generally got a crate trained dog - and can have the freedom to do things like run errands or be gone a few hours without fear of causing the dog a heart attack over it
Mikroma: Same suggestions in your case, though if his problem is primarily being separated from your husband, logically he is the one who's going to have to do most of the sitting outside the door being "gone".
As for how long all this takes - it really depends on the dog. Probably an average might be 2-3 weeks, but if the dog is really anxious, it might take a bit longer. Let his level of anxiety be your guide for how quickly you progress, as an anxious dog will take longer to cease paying attention.
No accidents in the crate since I last wrote. And if he whines to get our attention during crate time its usually to go to the bathroom 
