Wait, I’ll Change The Ending

I possessed the body of Ronnie Chaliganne, the villain of the popular manhwa .
5 years before the manhwa started.
What is this?
How come my favorite character is right in front of me? I heard that fan’s can be lucky. But this is absolutely the best! Since I’m not sure when I would return back, I decided to do my own thing and change the original work. I wasn’t aware that what I’m doing is affecting the whole story itself.
“Hey, you’ve been twisting the story in a very strange way, haven’t you?”
Five years later, a mysterious wizard came and suddenly blamed me. So he sent me here and now he’s giving me a chance to change the ending? And the remaining time for me is one year, and after a year, I would have to return to my original world.
One year is enough for me to change the ending.
In the original story, I really wanted to change the ending of my favorite character, who died with a broken heart. I thought that it was a bonus for me to watch him from the side…
But wait, my ultimate crush is suddenly proposing to me? Huh? This isn’t what I’m expecting to happen.
“You’re definitely my type. I’m not gonna let you go.”
The person you’re supposed to be obsessed with is the heroine. Not me! What should I do now? I think I just ruined the original story.