1
general::
Phrase(s): in the worst way
Fig. very much. • I want a new car in the worst way. • Bob wants to retire in the worst way.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Desperately, very much, as in He wanted a new trumpet in the worst way. This usage replaced worst kind. [Colloquial; second half of 1800s]
American Heritage Idioms