I'm sorry to hear that. I got the image online...
The image in question is sold here: https://en.clipdealer.com/photo/media/A:9855242
Freely distributed here: https://www.nicepng.com/ourpic/u2q8u2w7q8r5a9e6_bloody-handprint-on-wall/
And here: https://www.shutterstock.com/image-photo/bloody-handprint-streaks-on-bathroom-ti...
Photographer Shawn Hempel holds the rights to the image. Are you him?
If you show me some proof of origin/authorship or of your identity then I'll be more than glad to give you due credit, or even to remove it completely :)
Unfortunately, the original was made on a school computer. I don't mind you using it! I think it is great and I am flattered! I just was stunned to find something I made years later on the internet. Unfortunately, I do not know Shawn, but I might get in contact with him. Thank you, and please keep making games!