One thing I didn't know until mediation is that while my W and I were separated, I was supposed to pay child support based on our income differential. We had a 50-50 split of time with the boys, but I was supposed to pay child support, but I just didn't know that. I didn't notify my lawyer that my wife had moved out so my lawyer didn't know to tell me about the child support payments (I had to pay her a lump-sum at mediation).
If your state laws are similar (I live in Florida), then you may have some legal recourse to collect money from your WH.
