tax on bonus distribution

In a divorce agreement, my ex pays me 50% of his yearly bonus after he pays taxes on it. This amount varies each year, so it is not in our alimony or child support calculations. It is just a payout. He pays taxes on his bonus. So after taxes he might get a bonus amount of 50,000. He writes me a check for 25,000.  What do I need to do on my tax return?