1. Explicitly, calmly, presented in a logical way (x behaviour caused y feelings for z person).
2. Wait a few days for Ni to reorganize self-perception.
3. INTJ will approach you or you re-approach INTJ and have the real, in-depth conversation.
My personal experience has been that, because I'm a reasonably mature person, when I've genuinely had an issue to sort through that was a repeated issue re: how I treat others, it was a blind spot for me. Telling me in depth why it was an issue is not going to filter through. As soon as you give the #1 instruction (see above) our brains instantly branch off into a tree of infinite implications of cause and effect (one dimension for past memories, one dimension for current interactions, one dimension for our future interactions i.e. if I keep this behaviour up, in a decade, this will affect my marriage/kids in ways A, B, C, D...) Then we have to reorganize the way we understood reality in past, present and future. Then we xxTxs have to sort through our feelings because we've hurt someone else's feelings, if we're mature enough.
It's simply too much to give all at once. Let the Ni reorganize the brain then go for it.