Thanks for your interesting post and for sharing your thoughts so that it gives us the opportunity of pondering and commenting upon them.
When I read your post, it reminded me that there is a difference between 'normal' and 'natural' . It is a natural instinct to look back, which is probably why you say you can't help it. However, you are quite right to imply that looking back is not necessarily conducive to mental wellbeing, unless it is part of a therapeutic intervention.
Some fortunate people recover from the traumas of life by enjoying sitting in the sun, relaxing and letting the natural healing processes take their course. However, there are many more (which makes it relatively 'normal') who like to think they can get better by actively doing something about their situation.
Sometimes these artificial ways work and sometimes they are just sticking plasters that make it look as if you are doing something whilst the natural healing processes carry on anyway.
You don't say what sort of therapist you are seeing but most will listen empathetically to what you have to say and respond accordingly. Psychologically this is usually a great help in the process of coming to terms with the trauma. I only have slight reservations about therapists who make their living doing this and that is, there is a 'natural' tendency for human beings to look out for their own interests in any situation, which begs the question as to whether they have a vested interest in their clients getting better or maintaining the status quo so that they need the therapist indefinitely.
Many people use their pets in the same therapeutic way, feeling that the pets empathetically listen to their conversations even if they are rants about all the ills of society. Because so many people do this, it can be described as 'normal' - which technically means you are not 'crazy'.
Anyway, thank you again for stimulating my dwindling brain cells and I hope whatever you do will help you to cope with your life in future.