As someone who sees a counselor and who would like to be one eventually, they know it's not easy for most people to just open up to a stranger. The counselor, for the most part, is going to follow your lead as far as what you wish to accomplish in therapy and try to develop a trusting relationship with you in order to do that. My counselor knows that I have a tendency to put my needs after everyone else's and every thing else I feel I have to do. So while I don't bring that up in therapy, she recognizes it from what I've told her. It's an issue I need to work on because it ultimately affects my ability to do what I do.
As several people have already said, go in with an open mind. If you've already made up your mind that counseling is a waste of time or can't possibly help, then you aren't going to take much away from it. Give it a chance. You might learn a lot about yourself.
Your first session or two will be along the lines of getting-to-know you/ introduction. You'll likely have to give some background information, family history, health history, etc. usually in a few forms to fill out. The counselor should explain the process to you, ask for your expectations, your reason for being there, and get your thoughts on seeing a counselor. From there it will be up to the two of you to explore the issues you have brought up and how to approach "treatment" (I put it in quotes because treatment is often associated with medication or more severe interventions when really it usually doesn't involve anything more than finding a way to help you think about things differently).
Also, there are different "styles" of counseling so that stereotypical touchy-feely Mr. Rogers/female New Age guru is not the person you will likely see in that office. The person you are going to see through your department has probably got a lot of experience dealing with issues that are more specific to first responders and special training just for that purpose. If after several sessions you are uncomfortable with this person's approach, then find out if there is someone else to you can see. You won't benefit from dealing with a counselor who rubs you the wrong way.
Good luck, OC. It's not an easy road, but it will be worth the effort if you give it a shot.