Tameka Raymond -- Usher's Decisions Almost Killed Our Kid

Usher's ex-wife, Tameka Raymond, has filed legal docs -- obtained by TMZ -- in which she blames the singer for the near-death pool accident that landed their 5-year-old in ICU.

In the docs, Tameka claims Usher Raymond V was left unsupervised in the swimming pool when his arm got stuck in the drain. Tameka says Usher delegated his supervisory responsibilities to his aunt ... who she believes was not on the ball.

Tameka, who is asking for temporary primary custody of their two children, says it's typical that Usher delegates responsibility for their kids ... because he's out of town 85% of the time every month.

What's more, she says Usher had fired every caregiver who was on staff when he was awarded primary custody ... and she's clearly saying the replacements are not up to snuff.

In the documents, which were filed Tuesday -- the day after the pool accident -- Tameka wants decision-making power over the children's education, healthcare, religion and extracurricular activities.

The hearing has been set for Friday at 2pm ET.