if you must (do something)
idiomPart ofmust
if you must (do something) — idiom
1. You say this when you agree to let someone do something, but you are not happy a
1.idiom
Definition
You say this when you agree to let someone do something, but you are not happy about it.
Example
Dad said I could go to the party if I must.
If you must know, I bought the dress for the wedding.