If you are getting a divorce, you will need to update your will or your estate planning documents to reflect your changed circumstance. In some settlements or court orders, support obligations may be made binding on your estate. If that is the case, you need to ensure that your estate has sufficient funding to cover those obligations.
If you die before you are divorced but after separation, your separated spouse is not entitled to their share of your estate under the operation of the Wills Estates and Succession Act. It is good practice to do a new will after separation just to confirm this as the surviving spouse could say that you were not separated as a way to claim from your estate.