Magnanimosity
Begrudging benevolence.
The lottery winner showed quite a bit of magnanimosity when he donated his winnings towards his local disaster relief, after the flood. He didn't want to, but he knew it was the right thing to do.
magnanimosity
A blend of animosity and magnanimous, an insincere enthusiasm or friendliness hiding ill intent.
Magnanimosity is smiling at someone while you plot their death.