You can say you were **diplomatic** (adj) and acted diplomatically (adv) 


>- [**diplomatic**](https://www.merriam-webster.com/dictionary/diplomatic) - employing tact and conciliation especially in situations of stress.  e.g. "a diplomatic way to say no"

from the web:

[**1**](https://books.google.com.br/books?id=I_5gLih6Y7MC&pg=PA76&dq=diplomatically&hl=en&sa=X&ved=0ahUKEwiAy4TT8MHZAhUSylMKHemDDEw4HhDoAQhTMAc#v=onepage&q=diplomatically&f=false) -  While engineers must be careful not to pass judgment on a particular matter, engineers who are faced with this type of ethical quandary should make every attempt to carefully, delicately, and **diplomatically** sidestep the matter in order to remove any appearance of an ethical conflict.

[**2**](https://books.google.com.br/books?id=-VZNAgAAQBAJ&pg=PT98&dq=diplomatically&hl=en&sa=X&ved=0ahUKEwju-dfk8cHZAhVK2FMKHbfLAB84RhDoAQgsMAE) - Even when Quent explained that Jenny had earlier admitted going outside and chatting with a girlfriend, all Lucy had said was, “No harm done. I know the girl means well.” As **diplomatically** as possible, Quent had proposed that the children come to live with him ...