Hello sarac: I'm sorry I am not able to suggest what this might all have been about. Anything I would suggest would be simply a guess. I think to come to a genuine understanding of what was going on here, you would need to seek an opinion from a mental health professional. I noticed, however, this is your first post here on PC. So... welcome to PsychCentral!
I hope you find PC to be of benefit.
Since you mentioned this all started with major depression, here are links to two articles, from PsychCentral's archives, on the subject of psychotic depression. I don't have any way of knowing if this is what happened to you.
But it may be one possibility:
https://psychcentral.com/encyclopedi...ic-depression/
https://psychcentral.com/lib/psychotic-depression/