No. Talking to an attorney is a good step to protect yourself, and can help you make sure your rights aren't being violated during an investigation. Any privileged information you tell a lawyer can't be used against you. If you are unsure, ask the attorney about the privilege rule before getting into detail.
It's always cheaper and easier to get everything in writing now, before it becomes a problem. Plus, it's a good way to make sure all parties really are in agreement. If the amount of money you stand to lose is more than you're willing to walk away from, getting a contract in writing ahead of time will protect your interests and promote resolution of disputes.
Getting everything finalized will protect yourself and your credit against future claims. If you decide to remarry in the future, the process becomes much more complicated if you wait so long you've lost touch with your spouse entirely. If you really don't think you need or want a formal dissolution, at least be sure have an estate plan in place. Otherwise, everything may go by default to your legal spouse, no matter how long you have been separated.
Unfortunately, science has yet to perfect immortality, and the unexpected can happen at any time. If you have children, you especially need a plan in place so you know they will be taken care of. Many attorneys (including myself) offer free consultation. This can help you figure out what happens to your estate unless you specify otherwise, and whether you should use a will, a trust, a DPA, or some combination.
A Designated Power of Attorney is a special form often created at the same time as a will. If you're ever in an accident or become suddenly ill, and can't speak for yourself any longer, this will help your family know how to make medical decisions for you. It will also help your doctors know how to make the right call.
You're right that, by itself, the document won't be very effective. That's why it's important your family knows where they can find a copy of these documents if they need one. Having these documents ready can help lessen the stress on your loved ones at what will be a difficult time.