Mystery UK Celebrity Spiraled After Confrontation Over Alleged Sexual Misconduct

The mystery UK celebrity accused of sexual misconduct spiraled after receiving letters from two major news outlets ... and his personal assistant later stepped in during a suicide attempt ... according to new documents from the case.

TMZ obtained the filings detailing the anonymous star's battle to keep his identity hidden ... including testimony from his personal assistant, publicist and attorney.

According to the docs ... the celebrity received letters from ITN and The Guardian in May asking him to respond to allegations of sexual misconduct.

His personal assistant told the court the letters triggered an immediate and dramatic change in the celebrity's behavior ... saying he couldn't cope with the prospect of negative publicity and expressed a desire to take his own life.

The docs say things got so serious that the celebrity was voluntarily admitted to a psychiatric hospital that same day ... with his publicist saying he initially couldn't respond to the allegations because of his mental state.

But, according to the filing, the situation took another troubling turn in July ... when the celebrity left the hospital during a period of leave and attempted to take his own life. His personal assistant became aware of his movements and intervened, according to the docs.

In a recorded October conversation with his lawyer, the celebrity also claimed he'd concealed or downplayed his suicidal intentions to get hospital restrictions eased and eventually secure his release.

He also expressed fears that the allegations becoming public could destroy his relationship with his son ... a concern his legal team cited while fighting to keep his identity secret.

As TMZ previously reported ... the man, identified only as "PPT" in court, is accused of abusing his fame and influence to pursue inappropriate sexual relationships with much younger women. He has denied the allegations.

Judge Matthew Nicklin ruled the celebrity couldn't stop the allegations from being published ... but his name will remain undisclosed for now while he has a chance to appeal.

The judge did not rule whether the sexual misconduct allegations were true.