words fail me

I can't put my thoughts or feelings into words, especially because of surprise or shock, as in When she showed up at the wedding with all three ex-husbands—well, words fail me. [Second half of 1900s]

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.