If you have not already washed and dried the pillowcase here are some tips!
Cold water and meat tenderizer! Hydrogen peroxide is also another idea!
hometalk has some ideas:
Start with dabbing hydrogen peroxide on the areas that have blood,soak/ wash in cold water and a hydrogen based bleach product such as Oxyclean (you can find the equivalent at Dollar Tree).
homemade oxyclean: https://www.craftylittlegnome.com/homemade-oxiclean-recipe/