If I had spoken out like that, I would have betrayed your children

[TonyChanYT]

What exactly is the author saying in Psalm 73:15? What is wrong if he speaks out, and why would speaking out betray the generation of God's children?

Let's see the context. Out of frustration, the psalmist vented in NIV Psalm 73:

3 For I envied the arrogant when I saw the prosperity of the wicked.
4 They have no struggles; their bodies are healthy and strong.
...
12 This is what the wicked are like—always free of care, they go on amassing wealth.
13 Surely in vain I have kept my heart pure and have washed my hands in innocence.

The inflection point of his venting occurs at

15 If I had spoken out like that, I would have betrayed your children.

I.e., if I go on like this and advocate the easy life of the wicked, I would be doing your descendants a disservice. Now he dropped his horizontal point of view and looked to God.

18 Surely you [God] place them on slippery ground; you cast them down to ruin.
19 How suddenly are they destroyed, completely swept away by terrors!
20 They are like a dream when one awakes; when you arise, Lord, you will despise them as fantasies.

He turned to God's truth concerning the wicked and repented his earlier behavior.

21 When my heart was grieved and my spirit embittered,
22 I was senseless and ignorant; I was a brute beast before you. ...
28 But as for me, it is good to be near God. I have made the Sovereign Lord my refuge; I will tell of all your deeds.

He ended it on a positive note by stating his dependence on God.

What exactly is the author saying in Psalm 73:15?

He was frustrated by what he saw around him horizontally. In verse 15, he dropped his frustration and focused on God's vertical reality.

Don't get frustrated by the injustices in the world today. Doing so is teaching our kids the wrong lesson. Instead, find comfort in God's eventual perfect justice.