Life is full of tests. This unpleasant situation can be a test for your parents and you and other family members.
1. Try your best to talk very nicely to them and if you know respected persons who might have an effect on them, then try to request them to intervene.
2. Try to minimize the gap between them and request then not to mention bad things of other party.
3. Try to remind each of them about the good points of the other and the good times they had in their life together.
4. You are allowed to tell each of them stories about the love that he or she has in the heart of the other party. Islam gives big importance to efforts to make differing persons patch up. The Hadeeth says: Removing the rift between differing persons is more important than all the recommended prayers and fastings.
5. If they feel that there is no way for them but divorce, then try to minimize the damage as much as you can and try to face the situation with realistic attitude depending on the help of Allah who says in Quran about similar divorce cases (And if the separate from one another, Allah will grant each of them from his grace)(4:130).