1
general::
Undecided, midway between two alternatives, neither here nor there. For example, I'm betwixt and between canceling my trip entirely or just postponing it, or Jane is betwixt and between about accepting the offer. The adverb betwixt, originally meaning "by two," is seldom heard except in this expression, first recorded in 1832.
American Heritage Idioms
2
general::
Phrase(s): betwixt and between
1. Lit. between (people or things). • I liked the soup and the dessert and all that came betwixt and between. • I sat betwixt and between all the actors who weren’t on stage. 2. Fig. undecided about someone or something. • I wish she would choose. She has been betwixt and between for three weeks. • Tom is so betwixt and between about getting married. I don’t think he’s ready.
McGrawhill's American Idioms And Phrasal Verbs