the lesser of two evils

[Lucretia]

“You can either sell your house or get a fictitious divorce. It’s up to you to decide which is the lesser of the two evils”.
I wonder if the article is OK here or it is a set phrase, the lesser of two evils. It’s possible to use articles with numerals, isn’t it?
“ Mary wanted to serve them supper, but the two men were fast asleep in their arm-chairs”.
Thank you.

 

[AnnieF]

I think that although 'the lesser of two evils' is a set phrase, in this example you are citing two specific evils, so it's fine to use the article ...