The accusations of Tifa "lying" or somehow being at fault in any way have always seemed absurd to me. There's all that above, but even more so the fact that people seem to forget that she herself experienced the same profound psychological trauma, but also barely even survived the night. Her ass blacked out and was in a coma (again) for weeks or months and woke up alone on another continent with no idea (until half a decade later) how she even managed to get there.
If ol' dude shows up and is like, "I was there, the whole time, actually." The only logical explanation (from her perspective) is that she herself was remembering wrong. There's no guarantee that she has that she herself isn't suffering from fucked memory.