My main point is you also cheated using a third party program, so in turn, by your own logic, you are in fact a cheater. As cheating is defined as acting dishonestly or unfairly, in order to gain an advantage, especially in a game or examination.
Overlays offer a clear advantage over those who do not have them, and seeing as they are not allowed to be used by Blizzard themselves, that is a form of cheating.
As long as you stick to your own logic, that’s perfectly fine.