Okay, so I know the textbook rules when to use present perfect and past simple but for some reason I can't decide between these two:
I suddenly realized something.
I've suddenly realized something.
In both cases I mean that my realization happened at this moment. And even though "at this moment" is a time expression so present perfect should not be correct with it, I don't use that in the sentence, and I feel present perfect is usable but I don't know if that's actually correct. I also have a vague memory about reading somewhere that present perfect can be used to emphasize things in certain situations but I may remember wrong, I couldn't find examples of such usage while I was googling for answers.
Also, if this was not "at this moment" but in the past at an unspecified time, would the adverb suddenly indicate a specific time?