My suggestion is to first consult with another family law attorney. If that attorney thinks that malpractice was committed, he/she can refer you to someone. Since the underlying issue is regarding a family law situation, and you need an expert to say that your family law attorney's decision was a deviation from what an attorney should have done, my thoughts are to get yourself a good family law attorney first. That attorney can tell you and let yo know if what was presented at mediation was reasonable. What I am unclear about, is whether you have discharged or terminated your current attorney relationship. Hopefully, you can find someone to help you. Good Luck.
This forum is not for recommending lawyers. You can go to Avvo's "find a lawyer" tool, and you can go down the list of attorneys until you find help. You may want to offer to pay for an initial consultation if you are having problems.