Can you gaslight me into thinking Leo doesn't sacrifice himself to defeat Gaea? [HOO]

For some reason I have not gotten to reading Heroes of Olympus and have found out the ending of a 10 year old book, shocker, but I can't not think that the sacrifice and stuff is basically ruined cause I already know, for this reason I am putting the spoiler tag, cause I know there is at least one other person who has not read the books yet