Wow Chris...you are in such pain, its hard to read it.
I have been through what you are going through, so I know. There are very few life experiences that are harder than telling your children that one of their parents is moving away. I am praying for you.
I do still think there is hope for your situation, but YOU are the main concern right now, not the relationship. YOU must get through this for your girls, with or without your husband. YOU can and will be strong enough to do this, even though right now you feel like you'd rather die than get out of bed sometimes.
If you need to, go to your doctor and get on anti-depressants to help you get through this time.
It may take a long, long time to really get over it, so be kind and patient with yourself and don't expect yourself to just snap out of it or be happy all of a sudden. That *may* actually happen and many people surprise themselves when they do suddenly just get a lot better all at once (ephiphany stuff)...but this may NOT happen for a long time so be prepared that it could take a year or more before you feel normal again.