I like Drew's idea. Give her the facts and let her figure it out for herself. Is your child support fixed or is it an agreed sum between you and W?
Me: 31, W: 29 T: 4 M: 2 Kids: 3 (SS: 7, SD: 4, D: 3) Separated, still living together: Nov 2013 Separate bedrooms: Feb 2014 W working away; kids with me: Nov 2014
