This is by far the most destructive form of guilt. The reason it's so damaging is because you are taking irrational responsibility that is not yours to take. There's no way to learn a lesson from it, there is no action item, meaning there is no solution.
For wounded people, it's your conscious punishing you, it's an irrational emotion and it may cause havoc on your emotions because it often will distort your reality.
If you are suffering from unwarranted guilt, here is the process to stop it. It's a repetitive exercise to reteach your mindset truth instead of the irrational feelings and thoughts that are causing this unwarranted guilt. It only takes a few minutes a day and if you can do it several times a day, even better. No way to know how long it will take but don't give up, it will happen, those thoughts will stop.
1. Write out what you feel guilt for, as detailed as possible.
2. Now read what you wrote aloud and then ask yourself this question: What did I do to cause harm to this person? If it's unwarranted guilt then the answer should be nothing. Now, write your answer as a complete sentence, like this, "I did not do anything to cause harm to xxxx and I do not deserve to feel guilt." Read that back to yourself after you write it. The purpose for writing it out is that is resonates differently with your brain.
3. Spend 10 or more minutes every day reading your answer aloud to yourself. Eventually those feelings will disappear.