When a hang slip breaks a house apart shortly after a frustrated mum and wife just told her workaholic husband that she wants a divorce, the whole family has to work together for the last time and survive, by helping each other on the safe side of the house, while its pieces are drifting away from minute to minute and might fall from the mountain soon.

Minutes after telling her husband she wants a divorce their house is caught in a landslide. She must work with her family to save each other before the house collapses.

Still too wordy.

People would help perfect strangers escape. You may want to think of something that puts more pressure on them and would allow to decide not to help.

Your logline is a little long, and while the divorce will make a great B story in your script; in the logline you should concentrate on the impending disaster.