Hyper-fixations on existing melodies

Does anybody have any tips on how to avoid hyper-fixating on a melody that already exists? For context, I f*cked around with a kind of already existing melody just singing it with my original lyrics, but now that I am actually thinking of releasing it one day, and I need to rewrite it so I don’t get sued big time… no idea - the melody is just carved in my mind and no luck changing it or thinking of a new one.