I have a stack of photos that got wet and stuck together.

try putting them in a deep freeze. Cold usually contracts, but water will expand when frozen. After freezing them, let them thaw out A bit. Then try to separate cautiously

You can also use a blow dryer on low.

See what a museum might say ....

Soak the photographs for at least an hour in lukewarm water and gently peel apart. To dry those photos off either hanging them on a cloth-line or (if that is not an option), lay them down flat on a piece of cloth or paper towel to dry peacefully

Have you heard the expression freeze dried? That pretty much what you need to do with the photos.

You may have to freeze dry them aka freezer burn.