I know that neither of these topics is particularly cheery, but in some cases they do go hand in hand. If your marriage is going downhill, and you anticipate a divorce, or are in the process of getting divorced, it makes sense to take two immediate steps:
Name someone other than your spouse as your healthcare proxy; and
Revoke any durable power of attorney that allows your spouse to sign papers on your behalf, and designate a new power of attorney to act for you if you are incapacitated.
These two steps should be taken right away. As long as you are still legally married, these documents generally continue to be in effect, and as you probably know, a divorce can take a long time to finalize.
Comprehensive estate planning is important, but it is unrealistic to think that most couples can deal with it while going through a separation or divorce. Estate planning can wait a bit, but these other steps cannot wait. My office is happy to assist you with this, and credit the amount towards an estate plan, or if you are working with a family law attorney, he or she should be able to assist you with a new health care proxy and power of attorney.