One defuses a bomb.
I think the right answer is: defuse"
As Mr Trilby says, you defuse a bomb and you diffuse tension.
de·fuse /diˈfyuz/ Pronunciation Key - Show Spelled Pronunciation[dee-fyooz] Pronunciation Key - Show IPA Pronunciation verb, -fused, -fus·ing.
–verb (used with object) 1. to remove the fuze from (a bomb, mine, etc.).
2. to make less dangerous, tense, or embarrassing: to defuse a potentially ugly situation.
–verb (used without object) 3. to grow less dangerous; weaken.
"We have a problem, Houston." (LOL)
According to Merriam Webster defuse is the right word.
caused by his resignation suggests that the tension became widespread as a result of his resignation. diffuse: scatter or spread through.
In Dutch there is an expression:
'to take the fuse from the gunbarrel.' It is commonly used in the figurative sense. Given the interaction between the two languages, it is clearly 'defuse'.
Yes, diffusing is spreading out - you diffuse light to break it into colored bands ...
Diffuse is the should be. it spreads.