The dreaded INFJ delayed reaction. Have you been on the receiving end of this, or have you discovered it in yourself?
It's when you get a shock, particularly something in the nature of a friend letting you down or hurting your feelings big-time. This happens to me and I go into a kind of shock, I think. I may feel as though what has happened isn't really that bad. I may even tell them it's no big deal. Or if that isn't appropriate under the circumstances, I think to myself "oh well, that wasn't so bad after all. Hey ho".
Anywhere from 12 to 36 hours later - my true feelings hit me. Anger, sadness, disbelief, whatever.
What this has occasionally meant in practice is that I come back to the person and let them have it. Or even if I don't "let them have it", I dump a bunch more stuff onto them and they're like "But I thought you were ok with this? I thought we put this behind us already! I thought you forgave me!". And I can't really argue with what they're saying. It is kind of my fault, my bad.
I guess one solution may be to not react at all until you know what your reaction is. This may at least be possible if you get an email containing something which is going to be a shock (this happened to me recently.) I wrote back to the person fairly quickly, a kindly email - but by 24 hours later I was quite angry about a bunch of stuff that hadn't hit me the previous day. Fortunately I was able to vent to a mutual friend who also knew all about the situation and was quite understanding of my perspective. That helped. But the problem with this particular situation is that to a certain extent, I've gone on reacting and thinking of things to react to, over a period of several weeks. It's mostly behind me now but it did raise some tension with the other person when I brought a few more things up at a few later stages.
It's just, I have realised that this way of reacting to things has occasionally caused major difficulties in my relations with others. But what do you do if you literally don't know what your reaction is going to be in a few hours, days, or even weeks?