'No Words To Express This Pain'

Brittney Griner's wife says she's completely heartbroken over her wife's detainment in Russia ... saying in an emotional social media post, "My heart, our hearts, are all skipping beats everyday that goes by without hearing from you."

Griner has reportedly been kept in Russia the past few weeks after she was allegedly caught with vape cartridges in her bag while traveling through an airport.

Communication between Griner and her family has apparently been few and far between since she was taken into custody ... and Cherelle Griner said Monday morning it's all been excruciating.

"There are no words to express this pain," Cherelle said. "I'm hurting, we're hurting. We await the day to love on you…