(((rainbow)))
(I had someone who used to throw lit matches at me too. I thought that was a unique experience until reading your post!)

I think it makes sense that you can't just suddenly make a change of focus. And it really makes sense that you would rather be comforted by T, rather than think about what it felt like to be tormented by your brother! That is a hard place for your mind to go. Defensively and protectively your mind returns quickly to your T, something lovely rather than something demeaning and cruel.

It might feel like if you let your mind go someplace else, you will 'lose' T. But she's there with you all the while.

When you said she had to hold your hand, or else, it sounds like the scared little teased girl rainbow8, asking T to protect and comfort her. To be the adult who is there, not the adult that is 'not home' when protection and comfort were needed.