Why is the division of assets so difficult? Hilchos Gittin is clear how to go about it. Any assets either spouse brought in from before marriage remains with that spouse. Any assets generated during the course of the marriage remain with the husband.
The custody issue is more complicated. But Hilchos Gittin addresses that question as well. Some of the determining factors are the age of the children, whether they are nursing, their gender, etc. It, too, must be settled in accordance with Hilchos Gittin.