Dear British Labour Party supporters,
So, your MP, elected during the last general elections with your vote, does not accept the Labour Party leader elected by Labour Party supporters.
He/she is happy with your vote, but is unhappy with the vote you gave Jeremy Corbyn. This is how things work in a liberal democracy: your vote gave him/her gainful employment in Parliament; within your own party, your democratic vote isn't so profitable.
To put this another way: although they are ostensibly lambasting Corbyn, in reality you are the target of their tantrum. Put yourself in their shoes: they are unhappy with the leader you democratically chose, but they cannot afford manifesting their anger and contempt against you.
So, what's their way out?
Internal party democracy -- and you -- be damned.
He/she doesn't mind campaigning against Corbyn, even if by doing so a future Labour government becomes impossible: unable to punish you, his/her priority is to get rid of Corbyn; it's more important for him/her to impose his/her will than to represent Labour supporters.
Well, as a voter and Labour supporter you may feel worried and angered. I wouldn't blame you; I'd feel the same.
The fact is, these people are making Labour's position untenable, so that Corbyn's position is untenable. And, let's face it, Labour isn't going to win in those circumstances.
They preferred the nuclear option, and you are collateral damage.
Well, show them your justifiable anger and contempt in a civilised and democratic way. Give them what they want. Choose the nuclear option, you too. Come next election, if your current MP didn't support Corbyn and wasn't deselected, don't vote for him/her. Campaign openly and vote for someone else. If you ask me, I'd choose anything on offer, except for UKIP or the Conservatives. Realistically, is there any substantial difference between your anti-Corbyn MP and a Lib Dem?
"Ah, but that would be betrayal: we'll be weakening Labour. Besides, if we do so, we are stuck with Cameron;", you may oppose.
My friend, Labour is weak already and it was their doing. They had no problem betraying you. You owe them nothing, least of all loyalty: you owe loyalty to your family, your friends, your workmates, your class, not to them. Whatever you do, you are stuck with the Tories. Your MP made that unavoidable, not you. It was their choice; thank them for that: sack them. You have little to lose; they have plenty. That's the lawful and democratic way of hurting them.
The time to rebuild will come. As someone once told me: "Better alone, than in bad company".