Hello yellow_fleurs: I see this is your first post here on PC. So... welcome to PsychCentral! I hope you find the time you spend here to be of benefit.

I'm sorry I don't think I really know the answer to your question although I have had some experiences similar to yours. At what point extreme guilt switches from being distorted perception into a delusion is something I could not say. However here are links to 2 articles, from PsychCentral's archives, on the subject of psychotic depression. Perhaps some of the information in these articles will be of some help:

https://psychcentral.com/encyclopedi...ic-depression/

https://psychcentral.com/lib/psychotic-depression/

My best wishes to you...