Andrew File, 42, was speeding on the A701 near Tweedsmuir, in the Borders, in May 2012 when his car struck a vehicle being driven by Louis Henri Vaillant, 61. Mr Vaillant's 60-year-old wife Murielle died at the scene.
Earlier in the day File had been seen on the motorway between England and Scotland at speeds exceeding 90mph, the High Court in Edinburgh heard.
Airline pilot Paul Olin, 50, told the court File was taking corners on the A701 as if he was a racing driver.
File, of Sleaford, Lincolnshire, was convicted of causing death by careless driving following a week-long trial.
He originally faced a charge of causing death by dangerous driving. Trial judge Lady Rae deferred sentence until September 22 and warned File that custody was an option.