First recorded by Lloyd Brown (1964).
Hit versions by Peter & Gordon (US #9 1965), Cotton Lloyd & Christian (US #66/MOR #10/UK #51 1975).
Also recorded by Del Shannon, writer (1965).
From the wiki: “Del Shannon (‘Runaway’) wrote ‘I Go to Pieces’ for an R & B singer named Lloyd Brown whom Shannon discovered at a Detroit, Michigan nightclub. Shannon arranged and produced Brown’s recording but was unable to find a label interested in releasing the track. Shannon also attempted to record ‘I Go to Pieces’ for himself in an August 1964 New York City recording session but was unable to cut a satisfactory vocal of the song before his allotted three-hour session ran out. (Shannon would record a cover of his own song a year later, in 1965, after Peter & Gordon (‘A World Without Love‘) had already scored their US Top 10 hit with it.)