I don't agree with your generalization about everyone here. We are all individuals & have had different experiences. We have our own opinions.
I certainly don't think you are a "horrible person". I'm not sure many members think that. But you are without a doubt facing very trying times. Whether your wife has MDD, something else or a combination of things, the reality is that she is not able to contribute to your relationship or family right now. Perhaps it would be in everyone's interest for you to take some time away from her to spend with your children. I would encourage you to talk with a counselor or clergy before making that decision as a separation comes with its own set of challenges.
I agree with the others that once your wife gets on the proper treatment she will be back to her old self. But sometimes that can take a while. For me, I was put on the worst possible treatment regimen for my illness & the depression took a turn for the much worse. My family refused to talk to me, almost all of my friends wrote me off & it was a dark time in my life. But I was glad to feel like at least I wasn't taking anyone down with me. Once they finally figured out what the underlying cause of the depression was, I got on treatment & started getting better within the week. A year later, I was back to my normal self -- not happy 100% of the time, but back to work, back to caring about & visiting with friends & family, back to keeping up with housework, etc. I could be happy & active again -- something I had given up all hope of accomplishing when I was really depressed.
So I would encourage you to have hope for the long term, but if after carefully considering your options - ideally with the help of a professional - you determine that for a while it would be better to raise your children on your own, it may be that is the best option in your case.
wishing you well,