At the heart of New Covenant lament is the grace and mercy found in the forgiveness of sins. Even as the Psalmist was undoubtedly aware that Israel’s sins and disregard for the covenant had brought on the defeats and exiles, so we are aware of our failings. Yet, like the Psalmist, we focus on our faithfulness today and the hope for tomorrow. In fact, it seems to me that the Psalmist is quite unconcerned about past failings. Perhaps there is a lesson in that for all of us.

Over the past few days my heart has been heavy and lamenting. Even right now there is tears in eyes and my heart is breaking. The mistakes I made in my youth, haunt me today. I do have hope for the resurrection and the trumpet blast.But, right now I am so aware of my pain and that is may hurt someone I want to care about.
Yes, Come Jesus Come

I once had suggested to a class that lament without hope is despair, while hope without lament is utopian. I think that fits in well with what you’ve described above.

If you haven’t read Nicholas Wolterstorff’s Lament for a Son, I would highly recommend it.
DG