Take a look at the papers you were served. Usually the divorce petition includes standard Temporary Restraining Orders on both spouses, and one of those likely prohibits either party from removing minor children from the court's jurisdiction (basically your county or state) without written permission from the other parent.
However, if you're not really worried about your wife "stealing" the kids, it might be best for the kids if you sign off and let them go. But make sure your wife is aware that she needs your permission for that sort of thing.
As for you going, I don't see how your wife could prohibit you from going particularly if you helped pay for the trip. But do you really want to be cooped up on a cruise ship with the woman who just served you divorce papers? Might be more enjoyable to have a little time to yourself, and maybe plan something of your own with the kids that your wife can contribute to financially to even things up.
But that also raises the question, do your kids know about the divorce yet? What do you tell them if all of a sudden Dad isn't going on vacation with the family? If you and your wife haven't had a serious discussion about how, when & what to tell the kids, you need talk about that ASAP.