Having recently gone through one of these same periods of questioning, I find it's all part of moving forward. We reach some peaks, valleys and plateaus; then we forge the next bit of our path. Sometimes we take a turn in a different direction. Sometimes we plug along a little further on the same path. But, there is movement.
I do think the key for you is to eat life with a bigger spoon. Your wife may perk up and start to notice she is missing out/things are changing. Either she will awaken or she will not. If she does not, you will have some amazing memories of these years. And as your kids are young, it certainly can include them (and your w if she wants to join). Is she lethargic? Does she join in activities?
In my own depression I did begin to notice that others were quite engaged in the world while I was not. It was the beginning of the end of my depression.
Glad you are feeling better.
Me 41, H 47, M 15 yrs, S11, S13 BD 1: 11/4/14 we work on it; really I pretzel myself BD 2: 3/31/15 H goes down to "dorm room" 8/15: H back to MBR 10/15: H back in dorm room 1/18: H files, now divorced
