Sever ties/relations/connections/links etc (with/between somebody) verb phrase
To end a relationship
Mia has severed all ties with her sister for years.
The United States severed diplomatic relations with Cuba in 1961. Cuba and the US restored diplomatic relations on 20 July 2015.
The verb "sever" should be conjugated according to its tense.
This phrase emphasize that Christmas takes place once a year time, so you should grab this chance to indulge yourself and be good to others.
I've eaten a little more than usual as today is Christmas and Christmas comes but once a year, right?