woe betide you

"The Piano" を読み始めましたが、どうも話の状況が良く分からないので、巻末にあった The Making of The Pianoを先に読んで見ました。その中に興味深い表現が一つありました。
For Campion, the commitment of actors like those in this film was 'awesome': 'They bring with them a particular responsibility for their character, and woe betide you if you were to do anything to hurt their character or diminish them,'
"woe betide you" は慣用句あるいは連語の様です。例によって辞書で意味を調べます。
・Oxford English Dictionary: used humorously to warn (someone) that they will be in trouble if they do a specified thing: woe betide anyone wearing the wrong colour!
・Macmillan Dictionary: often humorous, used for warning someone that they will be in trouble if they do a particular thing; That was the rule, and woe betide anyone who ignored it.
・Cambridge Dictionary of American Idiom: also woe be unto somebody, bad things will happen to someone Woe betide anyone who plays Ann's CDs without asking her first. And woe be unto anyone who messes with my desk!
いつか使って見たい表現です。 Woe betide me if I forget this expression.