I could be wrong here, but just going off of personal experience, it's likely that what Calista is so hurt by is less the warning about insomnia and more about the fact that her T has reenacted a painful memory that she made a point of discussing with him (and that probably took some courage on her part since it's never easy to resurrect the wound of feeling humiliated).

What can make this kind of thing so hurtful is the belief/assumption that the T, ever aware and mindful of the emotional scar that the exact same act created, has nevertheless made a conscious choice to force you relive it (be it out of self-interest or malice). When I experienced this, I was in too much pain to have anything to lose, so I just sent my (former) T an email that explained - in as honest of terms as I could bear - how hurt and abandoned I felt that she had recreated something so painful for me and didn't find me worth sparing that pain. During the very next session I had with her, she went out of her way to completely counteract the experience she had caused me to relive. I don't think she would have bothered if she had really meant to cause me harm or in any way retraumatize me (especially since this involved initiating physical contact with me).

I'm willing to bet that your T likewise meant no harm, but you'll never know if you deny him (and more importantly, yourself) the chance to explain and, hopefully, make things right with you. In the meantime, my heart goes out to you, Calista, and I'm so sorry that you are having to experience such pain and sadness.