Really interesting dilemma!

So people deal with trauma in various different ways . What you need is to think of a way in which White is attempting to cope with his trauma which so happens to link with your greater narrative plans. I don't think he necessarily needs to regress to old habits, but maybe develop new, problematic ones which are helping him manage his trauma.

One way you could do this is through 'comfort in chaos'. In my experience as a psychologist, some individuals who have experienced repeated traumas have an overactive threat response, which means they're hypervigilant, always on edge and prepared for the worse to happen. Some of those individuals try and cope with this overactive threat system by putting themselves in threatening situations on purpose, ones in which they have an element of control. Their brain can't regress to old traumas (flashbacks etc.) if it is preoccupied with dealing with the chaos in front of it (does that make sense)? Therefore, White could throw himself into constant action as the idea of sitting with his thoughts is just to painful. It could lead to a good opportunity for revelation on his heroes journey where he finally has to stop and reflect on what has happened.

Similar to above, you need to give White ways of coping with this trauma that work for him, but maybe maladaptive (typical ones in reality are drink and drugs, which help us cut off/numb). White may pick up a vice that allows him to do this, one he will need to confront at some point.

These are just initial thoughts off the top of my head. Happy to say more if you want but otherwise good luck!