Hello- I understand how this can be very emotionally draining for you. It's strong of you to realize that maybe you vented to much information to your daughters. It's understandable that you would vent, and need to vent.
My parents got divorced when I was 19 and my sister was 14. We were old enough to form our own opinions and feelings towards our parents. (and yes, my mom and dad both vented to us at times, little comments here and there about eachother. It was hard to hear, and I think I lost a relationship with my dad in the begining because of it.)
I don't think parents realize how much kids 'see' and 'understand' during a divorce, I think even young kids can pick up on the unstable feelings between the mom and dad.
My advice is: I think you should defiently talk to your husband. He should not have thown 'I want a divorce' at you, and then ignore it for a month and take the kids on vacation like nothing has happened. It's unfair to you and unfair to your kids. The entire family is affected by divorce not just the parents. Your husband needs to be confronted, he can't make a drastic comment about divorce to you, then not have the balls to deal with the aftermath. It sounds like your husband wants you to do the his dirty work- it is very unfair to you and your kids. If you and your husband ignore the 'possible divorce' this could even further damage you and your kids relationships.