I'm not talking about shame. Shame is when you are convinced you are no good, you are not capable of doing better, you are pond scum. Nothing good comes of shame. But guilt is what happens when you have done a bad thing. It is your own conscience calling you to fix it.
Guilt is the emotional equivalent of physical pain.
Nobody likes to feel pain, but it's your body's way of saying something's wrong, get help. It's very dangerous to be numb, because you don't know you're the one who's bleeding until it's too late. Guilt is the same thing on a relational level. It's your heart's way of telling you something is wrong which needs to be fixed. Nobody likes to feel guilty, but if you become so insensitive, if you are numb to the people around you, you won't even know you're doing damaging.