Glad to hear you are getting counseling. Your C sounds like a wise advisor. I'd caution against rewriting the history of your marriage. If it was miserable, acknowledge that. But don't rush to that conclusion to try to soothe your current pain. That's easy to do, but I'm convinced it will not help heal you in the long run. If YOU feel you are losing something/someone you treasured in any way, go ahead and acknowledge that. Maybe the past does look different now that you've done some reflecting. Maybe it doesn't look as rosy now as it did at the time. I know I feel that way with my own sitch. Still, I feel a sense of loss and must work through that. The danger for us LBS is we rise above our feelings of loss as a way to avoid the pain. That provides some momentary relief but will not help us in the long run.
Also, ask yourself, hard as it may be, what your failures were i the marriage. You sound like you have handled the current crisis with her very well, but look deeper. What could you have done differently in the marriage? You cannot change the past, but you can learn from it to have a better present and maybe a better future too.