I never started therapy until I was about 37 or so. Once I started to feel better, I spent some time feeling awful for how many years were "wasted" from depression et al. It IS a thing to be grieved, in so mamy cases. My T helped me some by saying, "But there are reasons you waited until now for therapy. Maybe you weren't ready." It helped to think of it that way. We are where we are, after all. But it's still sad. I know what you mean.

gg