진작에 단단히 오해라도 하도록 터무니없게 만들어 버릴 걸, 하는 후회가 들어. => I regret that I didn't make it more confusing for them so they are suck with a completely wrong idea. It is a somewhat forced sentence very unlikely to be said in real life, since there's no point and it's not always possible to make someone misunderstand something.