**Also, try putting the photos in a tub of rice. Uncooked or course.
It will absorb the moisture.
They do this with tech gadgets.
try... taking them out and in the open air, not in direct sun.
Perhaps, if it gets drier, it can then separate.
in the future, store photos new and old, in a cool dry area in a well sealed box. With a desiccant in the box itself.
And, store the photos in archival acid free paper.... always. Or the photos will degrade.
If you unstuck them, as is, the photo will peel off.
You can try and ask a photographer... or archival specialist.
Ideally, if the photo is stored, with both front sides on top of each other... it will stick to each other over time. Because of the finish on the photo. Especially if it is a glossy finish.
Layering the photos with archival acid free paper, will prevent sticking from happening.