US election 2016: Trump and Romney's break-up battles

They used to be in a happy relationship, but now Mitt Romney and Donald Trump are going through a very bitter - and public - break-up.

Here are three of the insults the 2012 Republican presidential nominee hurled at his former friend - along with the current front-runner's typically bombastic responses.

Produced by the BBC's Olivia Lace-Evans

For more election coverage go to bbc.com/US2016