You have to realise that they will be much happier apart from eachother, and by extension you'll be happier too in the long run without all the arguments and fighting. I expect the first few weeks will be a little weird and will take some adjusting. I assume you saw it coming though, and they didn't hide it from you until the last minute, because that would be really stuff.
Are they fighting for custody or anything or taking eachother to court or are they being cool about it? Because divorces can get really loving ugly so you should be glad that they're not trying to sue the other into poverty (i assume they're not anyway)