how to split a single texture into multiple textures on separate objects in blender?

hello, I have a problem. I made a drawing, took a picture of it and imported it to blender as a plane (images as planes in on) then I edited and folded the image plane into the shape of the object. this worked fine, but when I imported it to unity the textures were gone. I found a fix to this problem by exporting it from blender with embedded textures, then in unity selecting extract texture. however, the texture that I imported as a plane into unity was cut and turned into several objects in blender, so when I extracted the texture in unity it just put one texture over all of the objects... is there a way to fix this? please help!!! here are some photos. this is the image plane inside of blender. notice the face on the cube.

this is the image plane imported into unity. (bellow) notice the cubes face is messed up and instead of being the multiple split texture planes it just put one big texture over everything.