Now, for the more intellectual response :) But first, I want to say, that this is an excellent topic and I like how you built it up, giving a personal experience (a very though one), and then also went into the common one here on hive. You gave a superb introduction to all kinds of philosophical considerations. To put them both together, psychology and philosophy, is doing them a favor.

My addition would be to stretch the field of this notion.

When another person's stress is transferred to you, can't it also mean that this reawakens your own stress that you thought you had overcome?

The strength of the other person's stress, I think, also can affect your stress-awakening potential.

But let's take just these two people in an environment of other people who are completely indifferent to this. The counter-transference of momentary stress of one by the other, I first hold as a fact, if both personalities are unstable (at least in the moment of emergence an instability reveals itself). You mentioned, you could call it a "phenomena" instead of a "disorder" and I would prefer this term, for its a more neutral one. Why not call it "Present Moment Stress Phenomena - PMSP"? :D (Oh, and lol to the pms! HaHa)

Then the simplest solution would be that both of them remove themselves from this countertransference situation and go into the company of the people surrounding them and thus calm down again. Since these others are indifferent to this form of transference, it will be an easy matter. The two people will then also have no difficulty in meeting again, since no one else will make a thing of it. The thing has no power.

As becomes quite clear, this pure and unadulterated form of indifference does not exist in the human environment. Where a stressed person confronts his environment with his experienced stress, it is like playing ticking. He ticks off the next one, who in turn feels his experienced trauma ticked off and seeks to get rid of it, as it were, by ticking off (confronting) the next one. And so on. On this vast playing field of ticking, we constantly and mutually remind ourselves of traumas suffered, in varying degrees of severity.

If I were the only person in the world with a suffered trauma, I would be a logical impossibility. So there would be nobody else who recognizes this as a trauma, also I could not recognize it as such.

Since the situation seems to be exactly the other way round, everybody has suffered a trauma, I move in a field of people who counter transfer their stresses.

Exaggeratedly one could say that all victims are perpetrators, because if they are not ready to transform their experienced victimhood as such (to re-evaluate, to reframe, to make a virtue out of sin), they hurt others who have nothing to oppose them in the moment of stress (they walk without the above realization). This then makes the formerly victim into perpetrators and they do/may not know it.

Thus it happens that a speech or deed seems harmless to the one who does it, when the one who receives it responds with courage and strength, while someone else breaks down, cries or screams. Or gives you a very cold shoulder.

As the experienced cannot be put back in the box, the trauma cannot be "un-experienced," but everything is and stays in the field. This means that the potentials are lying around and are like sleeping somethings. But you can treat these somethings in such a way that you find you don't need to wake them all up when a single one woken potential comes over you. Just imagine this field! Heeelp!!

From my point of view, there is nothing that can be completely erased from this realm of potentials. Even the opposite happens, so you try the deletion. Like ghosts or zombies, more of the potentials rise up, if one tries to erase them from the field. One could deal with them like with clouds: let them pass by. Nobody has ever claimed that this would be easy, right?

You expressed it as "commitment to not let it consume you is about the only way."
I agree.