DeepDiff among Rows

i have this data frame

import pandas as pd
from deepdiff import DeepDiff
df = pd.DataFrame({'col_new': ['a','b','c,d','d'],
                   'col_old': ['a','e','d','d'],
                   'col_val': [True,False,False,True]})
print(df)
  col_new col_old  col_val
0       a       a     True
1       b       e    False
2     c,d       d    False
3       d       d     True

i want to replace every False value with the DeepDiff of that row i tried this

df['col_val'] = df['col_val'].where(df['col_val'],DeepDiff(df['col_old'],df['col_new'])['values_changed'])

expected this

  col_new col_old                                            col_val
0       a       a                                               True
1       b       e  {'root': {'new_value': 'b', 'old_value': 'e'...
2     c,d       d  {'root': {'new_value': 'c,d', 'old_value': 'd...
3       d       d                                               True

but got this

  col_new col_old                                            col_val
0       a       a                                               True
1       b       e  {'root[1]': {'new_value': 'b', 'old_value': 'e...
2     c,d       d  {'root[1]': {'new_value': 'b', 'old_value': 'e...
3       d       d                                               True

Edit: I'd like to thank jezrael for his perfect answer.

But what if there are 10 or 20 columns, should I just type the same code over and over?

from DeepDiff among Rows