But if the artifact has been destroyed, and "X" is also fully aware of everything that happened to him, why would he not clarify with the new head researcher (or write the main article itslef)?
From the Foundation's/head researchers' point of view, reality has not changed, since they too have been altered to perceive the "new" reality as the default. The only one who has any recollection of the "old" reality is X. The destruction of the artifact only halted further warping of reality, it did not revert the existing changes.
The following is the intended structure of the article. I apologize in advance for the relative verbosity, as you specifically requested a brief description and it has become rather lengthy. Please also note that the terms surrounded by quotes will be replaced by appropriately technical terms in the actual article.
Containment procedures
A moderately comfortable living space, kept devoid of any objects which might be used for self-harm. The containment area is surrounded by "reality anchors".
Description of SCP-XXXX (researcher X)
X is described as a former Foundation researcher, who after destroying SCP-XXXX-1 (the artifact), has been imbued with a "reality distortion field", which is then concisely described. It is also noted that X claims SCP-XXXX-1 was warping reality and that certain events and people have now permanently been altered.
Description of SCP-XXXX-1 (the artifact)
After a short physical description, we learn that the artifact was confiscated by the Foundation for suspected reality-altering properties. Initial testing could not establish any anomalous effects and X destroyed it before any definitive verdict could be reached.
Preface to interview transcripts
We learn that X initially sought help for a suspected mental health issue. Furthermore, the Foundation's on-site medical personnel ran a battery of tests on X, but were not able to find any form of ailment.
Initial session with Doctor Y
X is worried about having a mental condition, as they have seemingly begun to confuse people's names and some locations within Site XX suddenly seem unfamiliar. By the manner in which X and Y interact, the reader is lead to the conclusion that X and Y are close friends.
Second session with Doctor Y
X claims not to recognize their quarters and that their quarters are now in a different part of Site XX. X is visibly distressed. Y states that the tests run on X after the first session did not show any signs of disease, but promises to run additional tests.
Third session
X claims their family has disappeared. Y is confused, as X and Y have known each other for years and Y does not recall X having ever been married. For the first time, X voices their suspicion that they are not going insane, but reality is being altered.
Fourth session
X no longer recognizes Y, claiming that sessions up to this point have been conducted by a Doctor Z, who is their friend. X has begun to suspect the artifact as the cause of the warped reality. Contains an addendum by the researcher writing the article that there is no mention of a Doctor Z in any of the Foundation's records.
Incident report
We learn that X was able to escape from the medical wing, which they were now confined to, pending transfer to a mental health facility, and was successful destroying SCP-XXXX-1. The act of destroying the artifact released "reality warping energy" and now causes reality to subtly warp around X, mandating containment as an anomalous entity.