I really really really recommend that you buy him out NOW. Take out a loan, give him the cash NOW. In exchange, be a bit more demanding some place else. For, he will find the $8000 up front very appealing for a variety of reasons. He can apply it toward debt, spend it on a new life in various ways.
The LAST thing you need is for him to have a business interest in your house for the next 5 years. It is SOOOO not worth saving a few thousand dollars here, trust me.
Don't tie the child support to the house thing. Get the amount you are legally entitled to. YOU can spend the extra to pay off a loan for the $8000 to get STBX clear of your house. Why set something up now that has to be renegotiated?
How does this sound?
(1) You pay him $8000 to get his name of the deed of your house, NOW.
(2) He pays you the full amount of child support, starting NOW.
(3) Keep all the exemptions for the kids -- he should be willing to do this for the $8000 up front. And, of course you will keep them for YOUR house.
