On collaborator conflict

If you are dealing with dozens, hundreds, or thousands of people, the odds that you will encounter personality disordered individuals is effectively 100%. Some such individuals can be extremely skilled with flattery, charm, charisma, and working people to maintain favor. It is not your fault that you were convinced by them initially; the onus is on you to resist continual cognitive dissonance.

I advise treating your collaborator like a mature, emotionally intelligent, high integrity, high-performing adult with a well-scaffolded personality who doesn't project, explode, blame shift, lie, enmesh, love bomb, invite caretaking, manipulate you into walking on eggshells, triangulate, decompensate, flare into triggered states, etc.

If they aren't that, I suggest moving on asap rather than tripling down on a quicksand situation.

It may be inadvisable to discuss maturity, morality, and reality testing lapses with someone on the personality disorder spectrum. They may be retaliatory and may live in a quasi-psychotic world of their own delusions which compete with reality for real estate. You may believe that you have been sharing close to the same reality when you never have been.

The longer you spend with them, the more "???!!?"-style moments will rack up: opinions and actions on their part that would be 0% possible of you or the structurally solid people you know and trust. Those moments are not to be ignored.

If you notice the person collapsing into mild panic or outsized emotion at the drop of a pin when it brushes their ego (eg the pin of obvious, neutrally-expressed statements of fact), it's a major clue that their personality is structurally unsound or structurally hypersensitive and prone to collapse. If this is the case, when they are in a triggered or decompensated state you may see them externalize aggression by lashing out in an unmitigated rage or internalize aggression by lapsing into self-abuse, self-trashing (eg drug and alcohol sprees, risky sex), emotional shutdown, splitting (seeing in black and white), stonewalling, switching into alternate self states, or spiraling.

Small but consistent flare-ups or mask slips — and any number of "what was that?" moments that accrue — may point to a clinical or subclinical personality disorder. This may be close to or literally incurable. Even if it is somehow able to be improved, it won't happen on the timeline you need; it will, if possible at all, take accurate diagnosis and perhaps decades of therapy with deeply skilled specialists, and will require the kind of self-awareness that clinically or subclinically personality disordered people may find extremely hard or unappealing to come by, due to their propensity to spiral and even lose touch with reality to varying degrees when faced with a proverbial mirror.

While I am usually a big fan of candor, these are likely situations where it will backfire. I suggest treading very lightly and quietly distancing yourself.