I am so glad to see these posts because I have much the same experiences. I torture myself with branching paths of reasoning that seem to go on forever into studies of the worst of my behaviour and they bring awful images that I can't get out of my mind.

I try much the same things as perpetuallysad but also, I try controlling my breathing and heart rate, thinking about some topic I'm really interested in, and for the images, I try to picture a blank white wall on a black background that gradually gets smaller and smaller until there's just black. It seems to help. There's no particular order I do them in, but I keep trying one after the other until something works, if anything.

I hope you can find something that works for you. It's awful, especially when you have a need to get up at a particular time and that just adds to the pressure of trying to get to sleep.

Take care.