In addition to having a formal appraisal, you need to have a home inspection. Yes, a home inspection. It will do you no good to only determine the value of the home if the home as some major issue that needs to be addressed. As a Realtor who specializing in handling real estate issue of divorcing couples we have learned that this is a best practice.
Absolutely, your best best is to have an appraisal done by an appraiser.
However, check with your divorce attorney first. He or she will be able to direct you so that all is handled according to the terms of the divorce.