Joey Lawrence's estranged wife's speaking out after filing for divorce ... saying pain leaks out with every tear -- and crying's always good for the bladder!

Samantha Cope -- who filed to divorce the actor earlier this month -- posted a video to Instagram Saturday filled with shots of her bawling her eyes out ... seemingly showing the emotion of her split.

Added in the vids were moments of pure joy ... dancing with her daughter, Dylan, in her arms and petting a horse on a ranch -- the emotional rollercoaster is real.

In the caption, Cope says a friend told her not to fear her tears ... but, to let them flow instead -- 'cause each tear is "God gently squeezing the pain and devastation from your heart to make room for new beautiful feelings to come in."

She jokes she also learned more tears means less pee ... so, sounds like Samantha's hoping to run to the bathroom less as her divorce battle rages.

We broke the story ... Cope filed for divorce citing irreconciable differences from Lawrence -- demanding 100% physical custody of their daughter with strict restriction on when Joey could see her.

To complicate matters, we also told you about a divorce filing for screenwriter Melina Alves and Edward Rider ... where Rider alleged his wife was having an affair with Lawrence. They worked together on the film "Socked in for Christmas." We reached out to Joey and Melina, no word back yet.

In any case, the breakup's seemingly hitting Cope hard ... but, she's not embarassed by her tears one bit.