Is quite complicated lol both the series and films are so confusing I dont think I will be able to explain it to you well, but the thing is in the original Shinji fucked up everything every single time (he actually destroyed the world)everyone pretty much hated him and if you add that to his trauma of his father hating him (thanks to this Shinji seeked his attention) he was devasted
So in the film he mets nagisa at that time (here is why he says he encounters shinji as enemy or as friend, in the series he is an "enemy" and has to kill him) he helps Shinji recover himself and try to amend his mistakes
BUT he fails yet again and nagisa dies again in Shinji's place this time
And in the end Shinji is completly liveless muttering kaworus name again and again
You should whatch the series and films is confusing but its worth it
Well I dont know if the manga has a conclusive ending and the light novel is only in japanese so no idea, sorry, but maybe in the wikipedia says something I remember checking it out and it somehow help me to understand it better
https://es.wikipedia.org/wiki/Neon_Genesis_Evangelion
It was refreshing and touching. The art was really beautiful as well. I don't know the actual, original manga so I can't really understand which is sad because I'm missing on something great. Would anyone like to explain it to me? (●'◡'●)ノ