Toxic shame is experienced as inner torment, a sickness of the soul. If I'm an object that can't be trusted, then I'm not in me. Toxic shame is paradoxical and self-generating. There is shame about shame. People will readily admit guilt, hurt or fear before they will admit shame.
Toxic shame is ghe feeling of being isolated and alone in a complete sense.
Any human emotion can become internalized. When internalized, an emotions stops functioning in the manner of an emotion and becomes a characterological style. You probably know of someone who could be labeled 'an angry person', or someone you'd call a 'sad sack'. In both cases the emotion has become the core of the person's character, her identity. The person doesn't have anger or melancholy, she is angry and melancholy.