If you mean the book “Heavens to Betsy! & Other Curious Sayings” by Charles Earle Funk, you will be glad you didn’t buy it, as the author’s answer on this one is:
Q. I am looking for the origin and meaning of the phrase ‘Heavens to Betsy’. [Mark Lord]
A. The meaning is simple enough: it’s just a mild exclamation of shock or surprise. It is almost exclusively an American expression,
associated in my mind with mature females of the Prohibition era or earlier (though this may just be a reflection of my recent
reading). As to where it came from, nobody has the slightest idea. It seems to be one of those traditional sayings that have been
around in the language for generations, but which only latterly have come to be recorded in print. The big Oxford English Dictionary has a first citation from 1914, but I’m told it can be found as far back as 1891. Some have tried to trace it to the Revolutionary War and to Betsy Ross, but have failed; others think it may have something to do with the frontiersman’s rifle, often called ‘Old Betsy’, but there’s no evidence that saying and name are associated. Charles Earle Funk, who in 1955 used the phrase as part of the title of a book about curious phrases, said that its origins were “completely unsolvable”. We have to leave it as one of
the great mysteries of lexicography, along with the similar ‘heavens to Murgatroyd’. Unless someone reading this knows different?
P.S. I, and about a zillion other Americans, emailed Michael about Snagglepuss so don’t bother.
Here’s a totally WAG, based on saying it out loud over & over. Perhaps it was originally “Heavens To Bits”, as if everything’s falling to pieces. Then it transmuted to Betsy. Maybe reaching, but since no one seems to know…