Leaving him alone and living my own life isn't working

[Sunfl0wer]

(I posted this another board too, I hope I'm not doing posting wrong)

My uBPDstbexbf and I live together just two more months.  It seems like we are both detaching in our own way, I'm fine with that.

He has been withdrawing, has painted me black.  He acts like he is scared of me even though nothing has occurred for him to feel that way.  I just imagine he is reliving some trauma of his past and projecting me as a villain. 

I'm afraid if I do not approach him and try to "fix" his emotional state that he will go deeper into his projection, flip from victim to aggressor in a reaction to whatever he is dealing with.

His behavior is triggering my own PTSD of hypervigilance and my startle reflex is sensitive. He is in-tune to my PTSD and when I react scared, he falsely assumes I painted him a villain, then he projects, paints me a villain, then takes on a fearful victim role that lasts till something flips or bursts it.   

My PTSD response usually only lasts a few seconds, I calm down, I know the difference between reality and triggers and move on quickly in that moment, more like a quick sneeze.

However, his uBPD response lasts until he can confirm I am a villain.  It can go on for weeks until he can build a case, get proof, pick a fight, make a false accusation and paint me blacker.

How do I keep things calm for next 2 months?  Do I validate him?  Give him some planned narcissistic supply?

(Leaving him alone and living my own life isn't working.)