What logic? Your sad-sack bullshit is nothing but a string of excuses for wallowing in your own self-pity.
She wasn’t IT. There is no “person to end all persons.” She’s just some girl you fell in love with, and yeah, it hurts like hell when that kind of thing falls apart, but at some point you gotta get your shit together, dude.
There’s no such thing as soul mates. At best, we find a life partner or two, and this last girl isn’t gonna be one of yours. Another girl might be, but you gotta pull your head out of your ass and move the fuck on.
Also, relationships aren’t a zero-sum game. This shit isn’t a competition. She didn’t find someone better than you. She found someone better for her — in other words, someone with whom she is more compatible. That’s not a reflection on you unless you need it to be for all that wallowing you’re doing.
The only way to really fuck up your life is to let yourself stay emotionally paralyzed. Don’t be a fucking loser. Start moving on, and quit looking for reasons not to grow and change.
(Oh, and that shitty little voice in the back of your head that just whined, “moving on is easier said than done,” that’s the voice you need to start telling to shut the fuck up.)