It can't be both ways. Either the past happened and the characters are unaware of the events, including what they said and what was said to them. Or, the past happened and all of the characters remember the events, what they said and what was said to them.
From what we see at the end, none of them, including Trubel herself, have no clue as to what happened, what Nick said to them, or what they said to him.
What Nick said in another dimension has no weight when he comes back through that mirror with Juliette. So for Adalind, the fact that he told her he loved her in another dimension does not work in the current one.
Nick may have told her he loved her, later on, out of audience earshot. However, it's just as easy to speculate that he never said those words to her as well.
From what we see at the end, none of them, including Trubel herself, have no clue as to what happened, what Nick said to them, or what they said to him.
What Nick said in another dimension has no weight when he comes back through that mirror with Juliette. So for Adalind, the fact that he told her he loved her in another dimension does not work in the current one.
Nick may have told her he loved her, later on, out of audience earshot. However, it's just as easy to speculate that he never said those words to her as well.
The best way to frustrate a cyberbully is to ignore him.