By the way, as an addendum to what I said about it being a very good thing for Cullen to have a positive relationship with a mage:
I've said this before, but I think it's hugely significant in Cullen's trauma that he was not only tortured but betrayed. The ones who hurt him were people he saw day in and day out, with whom he had at least a working relationship, who he probably thought he had a rapport with. Suddenly those people became his tormenters.
I don't think Cullen would have been as deeply damaged if he had been tortured by mages who were strangers, say, or his enemies. I'm sure he would still have been traumatized, but he wouldn't have that additional layer of being subjected to physical and mental abuse at the hands of people he knew and maybe even had some level of trust in.
So Cullen has to get over not only being tortured, but being betrayed by mages he thought he knew. I think that is a major factor in his reaction to mages afterward.
If he could learn to trust a mage who earned that trust, and knew he could rely on that person's support, I think it would help his healing process.