“That’s not a proper apology! You’re just justifying yourself!”
It’s very likely that you have said those words to someone else and had them said to you too. I know I have.
What I find interesting, in a quirky kind of way, not seriously interesting, is that both “saying you are sorry and meaning it” and “justifying yourself”(or another, or an idea) are meanings that the word “apology” convey.
Around 155 AD or CE (take your pick) a man who came to be known as Justin Martyr wrote his first apology. This was a defence of Christians and Christianity, to the Roman authorities which were persecuting some Christians at the time. This defence meaning is the original meaning of apology I believe (sorry if I’m wrong about that) so it’s quite funny I think, to recall times when I’ve told someone off for defending themselves because “that’s not a proper apology!”