Why the memory gets blurrier the more you check it
You started with a confident version. Now the details drift and the haze reads as guilt. Memory is reconstructive in everyone, and under inspection it behaves as if you have something to hide.
When this started, you could remember the evening reasonably well. Now, after months of going over it, you cannot. Details have shifted. Things you were sure of have gone soft. There are gaps where there used to be a sequence, and the gaps are the worst part, because a gap could contain anything, and a person with nothing to hide would surely remember.
I want to explain what is happening to the memory, because the blurring is being read as evidence, and it is evidence of something quite different.
Memory was never a recording
The picture most people have of memory is a video file: stored once, played back on demand, the same every time. It is wrong. Memory is reconstructive. Each time you recall an event, you rebuild it from fragments, filling gaps with what is plausible, and then you store the rebuilt version over the original. Recalling is rewriting. This is true of everyone, about everything, and it is why eyewitness testimony is so unreliable and why family members remember the same Christmas differently.
Under ordinary conditions, this does not matter. You recall the evening once or twice, the rewrite is minor, and the memory holds its shape.
What repeated inspection does
Now consider what you have been doing. Recalling the evening forty times, a hundred times, each time under anxiety, each time searching for a particular thing, each time asking: did I? What if? Was there a moment I have missed?
Every one of those recalls is a rewrite. The anxious search imports possibilities: what if I did this, what if that happened. The possibilities get rehearsed alongside the memory, and rehearsed images use the same machinery as remembered ones. After enough repetitions, the possible and the remembered are hard to tell apart. Details you imagined acquire the feel of things you saw. Details you saw fade, because they were not what you were looking for. The confident version you started with has been overwritten, piece by piece, by the investigation.
The blur is what memory does under this much handling. Any memory, inspected this way, behaves exactly as though its owner had something to conceal.
The trap of the gap
Once the gaps appear, they become the focus, and the logic runs: I cannot remember that part, so anything could have happened in it. But absence of memory is not memory of an event. You also cannot remember what you were doing at 3.14pm on a Tuesday six years ago, and nobody takes that as evidence of anything. The gap feels significant only because the fear is standing in it.
False memory
This is the mechanism by which the false memory half of this theme works. There may never have been an event at all. A doubt arose, could I have done something, and the investigation began, and the investigation manufactured a half-memory out of rehearsed possibilities, and now the half-memory is being investigated in turn. People come to me genuinely unable to say whether something happened, and it is not hidden: the search has produced a memory-shaped object with nothing behind it.
Stopping the rewriting
The only way to stop the memory degrading is to stop handling it. This is the response prevention in CBT with exposure and response prevention for this theme: when the doubt arrives, did I, the practice is to let it stand unanswered and not go back to look: no reconstructing the timeline, no rereading the messages, no checking the reaction. The memory, left alone, stops being rewritten, and the doubt, given nothing to feed on, subsides.
This is not indifference to what happened; it is a refusal to keep manufacturing evidence out of a process that cannot produce it. What we are not going to do is establish what happened, because the establishing is the compulsion and it is what has been eroding the memory all along.
For this theme, inference-based CBT is also a strong fit. Most of your evidence for the feared version is not evidence at all; it is a chain of reasoning about what could have been true, running over the top of what you actually remember, and I-CBT takes that chain apart.
If the memory has been getting worse the harder you look, there is more on how I treat real event and false memory OCD, and the looking is where we start.