That is a tricky situation - one the school should probably give a little more thought. Having said that it could also be a way for your children to come to acceptance and the school should be able to offer help.
I think that talking about it in a natural way amongst yourselves will help you discover what they are and aren't comfortable with. If you can deal with the feelings that are most distressing to them or hurting them it will help them to heal and understand and will also help them to know how to vocalise what they are comfortable with when a non-family member asks.
If it can't be discussed openly at home it will be all the more difficult for them to discuss in a social situation.
Remember children need to be taught how to understand and label their feelings. A child in this situation is experiencing feelings that most children wont identify with for many years and will need help sorting through the array of confusing emotional messages their brain is experiencing. I think if you can help them to sort through these feelings, label each of them , express them and discover why they are there you will be on the road to helping them accept the situation life has thrown at them.
Once they have been through this process "divorce" wont sound half as ugly, it will be another word to describe another situation instead of a word filled with confusing emotions and negative connotations.
My first marriage fell apart and I had a lot of trouble with the word divorce, until I really went through and analysed what I was feeling and sorted through it and accepted it, then it ceased to be an issue when I had to tick the divorced box instead of the married box on govt forms.
A key factor in helping your children deal with this situation is that you need to have dealt with it yourself. They will be guided by you in this. I wish you strength and courage, self-analyzing can be a confronting expedition but is well worth it. If you help your children while they're still young they will come out strong and self aware.
Also remember there are lots of support groups for yourself and for your children, you need not handle this alone.
It is so great that I got such decent answer.
I thought this question will be left unanswered as everyone on the site seems so lucky that all do not have such problem to deal with.
(Sure, they have time concerning their child knowledge as they dont hv to deal with these)
God bless u and have a happy life, we must get strong alone
yet , still , not telling the others will be better , otherwise , children will be looked down for not having a normal family
also , difficult to stand out if they got unfair treatment