my_list = [91, 13, 19, 25, 35, 3, 9, 11, 0]

print("The list is :")
print(my_list)

my_key = 2
print("The key is ")
print(my_key)

my_result = []

for element in my_list:
   if element + my_key not in my_list and element - my_key not in my_list:
      my_result.append(element)

print("The resultant list is :")
print(my_result)

The list is :
[91, 13, 19, 25, 35, 3, 9, 11, 0]
The key is
2
The resultant list is :
[91, 19, 25, 35, 3, 0]