I agree with this completely

The APA simply defines trauma as 'an emotional reaction to a terrible event'. This could easily be applied to multiple events...and a long-term trauma could result in a long-term reaction (or significant developmental changes!)

Invalidation seems like a common theme in my exploration and personal experience of BPD. It could also be the cause of our signature 'black and white thinking.' If I am sad, my feelings are invalid and perhaps punished, I am BAD. If I am happy then I am GOOD, my feelings won't be understood but they won't be punished either. There is no grey area because none of my feelings are valid anyway: I am BAD or GOOD, happy or sad, uncomfortable or comfortable... Period.

Just a thought, but fears of abandonment could be a direct cause of this too (just an opinion, not a fact). If someone who has only experienced an environment of invalidation and is then presented an environment of validation, then, even subconsciously, he/she could be trying to hold onto that. What if they leave me? Who will then validate me and my sense of self?

If invalidation is consistent , I think a poorly defined and SELF-VALIDATED sense of self could result...
If this is not considered trauma, I don't know what is. Great topic, ava.