OK

I would treat it as a gift since you got no 1099.

I would think you need some kind of Tax form for filing this, but if you don't want to get a letter from IRS I would suggest checking on line at IRS.gov or call a Tax expert. Just to be sure, if it's done wrong IRS will notify you 2 or 3 yrs later and you might have to owe them something. So it wouldn't hurt to find out and do it right the first time.

Its really going to depend on some wording and if it's a settlement or a suport check. If its spous support its taxable for sure and he gets to write it off ( federal taxes ) but if its simply a dispersment of funds generated while you 2 were married then you need to look at the tax filing for the year it may / maynot have been deducted.