I have had several clients through the years who have shared their feelings of guilt or shame over things they have done or not done. For my money, I find those two emotions unproductive.
Here's the thing: If you have done something to hurt someone else, think about what you need to do to remedy the situation. Apologize, make reparations, change behavior as needed—and then let go. If you simply feel guilty or ashamed and do nothing about it, you will be drained of energy, confidence and joy. And that's what you'll be passing around to others who are in your presence. So how does that help you or those around you?
Often the shame is less about a specific situation than a generalized feeling about not being "enough." Not being good enough, kind enough, thoughtful enough. Perhaps you think you didn't treat your parents as well as you might have wished. Or your children. Stewing over it years later doesn't fix anything. Rather, it holds you back from living a happy, healthy life now.
See whether you can release the guilt and shame. It may not happen overnight. But bit by bit, you can choose to examine the guilt to see whether there's any basis to your feeling that you've come up short—and then forgive yourself. Let go. Forgive yourself again. Let go again. And change whatever needs changing so your life can be productive, happy and healthy going forward.