Truth is a flashlight, not a bat. Use it to show, not to swing.

Honesty used to illuminate and honesty used to injure can carry exactly the same words. The difference lives in what you want afterward: for the other person to see something clearly, or for them to feel the hit. Once the second motive is in the room, accuracy stops being the point and turns into the permission slip.

Before you say the hard thing, ask what you want them to be able to see when you are done. If the answer is mostly about what they deserve to feel, wait. The information will still be true tomorrow, and you will be steadier.