I would say that "being abrasive" may be something wrong that you did, but it's not something fundamentally wrong with you. This is a little tricky, but I'll try.

The distinction is one of actions being wrong versus people being wrong. In either case, you may feel bad because you were abrasive, but the "object that the badness is associated with" is different.

If something that you do is wrong, then it's possible for you to change that in the future. You were abrasive, but you recognize that it was wrong to be abrasive, and as a result you may do something so as to not be so abrasive in the future. Once you change your behavior, you can stop feeling bad, since the feeling-bad has achieved its purpose: causing you to act differently.

But if what you are is wrong, then the feeling of badness is associated with what feels something like "your fundamental essence". It's not just that the abrasiveness was bad, it's that the abrasiveness was a signal of something that you are, which remains unchanged even if you manage to eliminate the abrasive behavior entirely. So even if you do succeed in changing your behavior and the people that you hurt forgive you, you may continue to feel bad over once having behaved that way. In which case the feeling of badness isn't serving a useful purpose anymore, you are just feeling generally bad for no reason.

Also, "realizing that there's nothing fundamentally wrong with me" doesn't directly eliminate guilt. As I understand it, guilt is a feeling that you've wronged someone and need to make reparations. That's about actions rather than your character. What's eliminated is something like shame, which I understand to be the feeling of there being something wrong with you. Interestingly, I feel that eliminating shame may make the guilt easier to deal with productively: since there's often a concrete approach for dealing with guilt (apologize and make reparations until the other person forgives you), you can focus on just making that happen. But because shame is a feeling of fundamental badness that can't really be dealt with, the only possible reaction is to try to suppress it or avoid it. Which means that if something that you did causes you both guilt and shame, the shame may cause you to flinch away from thinking the whole thing, and then you can't do anything that would help with the guilt.

On a functional level, both my intuition as well as my cursory look at relevant emotion research suggest that one of the functions of shame is related to a fear of moral condemnation. Suppose that you say something abrasive, and you also live in a society where abrasive people are generally looked down upon, and where it's hard to be forgiven for abrasiveness. Shame, then is something like rolled-up metacognition: it acts as a judgment of "if other people found out that I have been abrasive, they would judge me harshly" and motivates you to do things like hide or deny your past abrasiveness, or at least punish yourself for it before others do.

But subjectively, shame usually doesn't just feel like "I need to hide this so that people won't judge me", it feels like there's a fact of the matter saying "I am bad for having done this thing". "I am bad" is the brain's social-punishment machinery acting on the person themselves. Even if it is genuinely the case that you have done something that you would be better off hiding from others, it's better to do that without your social punishment machinery kicking in. Because as the linked article covers, your punishment machinery doesn't actually care about finding solutions to problems, it just cares about punishing you:

You can want to end death, disease, and suffering, without rejecting the reality of death, disease and suffering.

Moral judgment and preferences are two entirely different and separate things. And when moral judgment is involved, trade-offs become taboo.

When Ingvar was procrastinating, and felt he should do his work faster, his brain spent absolutely zero time considering how he might get it done at all, let alone how he might do it faster.

Why? Because to the moral mind, the reasons he is not getting it done do not matter. Only punishing the evildoer matters, so even if someone suggested ways he could make things easier, his moral brain rejects them as irrelevant to the real problem, which is clearly his moral failing. Talking or thinking about problems or solutions isn’t really “working”, therefore it’s further evidence of his failing. And making the work easier would be lessening his rightful punishment!

So when moral judgment is involved, actually reasoning about things feels wrong. Because reasoning might lead to a compromise with the Great Evil: a lessening of punishment or a toleration of non-punishers.

This is only an illusion, albeit a very persistent one.

The truth is that, when you switch off moral judgment, preference remains. Most of us, given a choice, actually prefer that good things happen, that we actually act in ways that are good and kind and righteous, that are not about fighting Evil, but simply making more of whatever we actually want to see in the world.

And ironically, we are more motivated to actually produce these results, when we do so from preference than from outrage. We can be creative, we can plan, or we can even compromise and adjust our plans to work with reality as it is, rather than as we would prefer it to be.

After all, when we think that something is how the world should be, it gives us no real motivation to change it. We are motivated instead to protest and punish the state of the world, or to “speak out” against those we believe responsible... and then feel like we just accomplished something by doing so!

And so we end up just like Ingvar, surfing the net and punishing himself, but never actually working... nor even choosing not to work and to do something more rewarding instead.

Hmm, interestingly I don't feel like any physically painful experiences have given me significant trauma, even though I've had broken bones a few times etc.

I think this is because I've generally felt socially supported during those times, and confident that the experiences will eventually pass: my impression is that a feeling of helplessness plays a big role in whether a physically painful experience gets interpreted as traumatic or not. So in principle giving your past self affection and a feeling of being safe and supported could also help with that. At least that would be my guess based on my limited experience.