Take a picture from only the half of the paper and post it here, no one can help you based on speculations, we need to see what you are up against.
I said we, not that I am an expert or anything, figure speech.
Sorry, but for security reasons I will not post any images. I have tried a mini microscope, increasing resolution, sharpness, and all the other stuff and I can't see anything. I know for sure that this is a WIF prvkey with 51 symbols as it starts with 5.