Victoria Fabian, 33, suffered extensive leg injuries in the blast in a car park behind the home she shared with Nicholas Fabian, also 33, in Highview, Vigo, Kent.
Her eight-year-old son, who was in the car with her, got out of the passenger door unscathed while her unborn child also escaped unharmed, Maidstone Crown Court heard.
Graham Reeds QC told jurors Fabian was a reservist after serving in the army between 1994 and 2004, and had been called up to do a tour of Afghanistan in January last year.
Reeds said: “It is the prosecution case against him that during the course of his weapons training he stole a hand grenade from a firing range in North Yorkshire, and on the 5 March last year he used it to booby-trap his wife’s car.
“He had the intention of causing an explosion that would kill her, or at the very least, to cause her really serious bodily harm and to endanger her life.”
The court heard that Victoria Fabian suspected her husband of having an affair with a woman he had met through work named Jackie Phillips.
Reeds said that analysis of his mobile phone showed he had sent her a number of text messages proclaiming his love for her in the days leading up to the explosion.
Jurors were told that Victoria Fabian wrote her husband a letter confronting him about her suspicions and also over a credit card debt of £1,400 (€1,663) she had discovered he had run up.
The barrister said there were two opportunities for Fabian to have planted the device in his wife’s borrowed Mazda.
He said the first was later that night when she went to bed and he went back downstairs.
Fabian denies attempting to murder his wife, along with a charge of causing grievous bodily harm with intent and one of causing an explosion likely to endanger life.
The case continues.