I think taking any advice given here isn't a good idea. No one understands your mental state or the root cause of your depression, and further no one here is li

I think taking any advice given here isn't a good idea. No one understands your mental state or the root cause of your depression, and further no one here is likely to be a trained mental health professional. Given your current state of mind, I think it's important to have real conversations with real people in the program and otherwise. Potentially see if you can get some time with a current student in the program or with a trusted advisor. Based on your list, there doesn't seem to be any real downsides to taking the fellowship and pursuing a PhD. If you drop out, I wouldn't necessarily see it as wasting anything. You learn valuable skills in a PhD that are certainly transferable. The age old advice for pursuing research is only do it if you're interested in it.