Be caught in the crossfire = be involved in an unpleasant situation in which people are arguing with each other, though you do not want to be involved.

• They say they are caught in the crossfire between the education establishment and the government.

Burn one’s bridges (boats) = do something which makes it impossible to return to an earlier state.

• I think you really burned your bridges when you announced you were quitting and proceeded to insult your boss in front of the whole staff.
• She’s young, so I don’t think she realises that she’ll be burning her bridges if she goes to work for their competitors.

When it comes to the crunch = when a situation becomes extremely serious and a decision must be made.

• If it comes to the crunch and you and your husband do split up, you can always stay with us.
• If it comes to the crunch, I’ll resign over this.