Cambridge Crown Court heard how Sharon was frightened for her life, thinking French was going to take her away and kill her.
Sharon, who had begun running back towards her office screaming for help, was heard by a colleague who came to her aid and pushed French off her.
She told police French had subjected her to emotional, physical and psychological abuse throughout their marriage after they got married in 2004.
She decided to leave him after she worked out he had blocked a number of people in her mobile phone.
Cambridge Crown Court heard how French committed the offence while on a life licence following a period of almost six years in prison back in 2006 after he set fire to an ex-partner's home after their relationship ended.
He was arrested a day after the incident on November 4 last year when officers found him in a pub car park in Grantchester, Cambs, and was later charged with attempted kidnap, taking a vehicle without the owner's consent and possessing a bladed article in a public place.
He was also charged with burglary after officers found evidence of him purchasing an angle grinder, masking tape, cable ties, a hacksaw and a drill, which he used to break into his estranged wife's home.
He then stole her spare set of car keys and wedding rings before making his way to her place of work.
French pleaded guilty to three out of four of the charges, but denied attempting to kidnap his ex-wife, claiming all he wanted to do was speak to her and get answers as to why their relationship had ended.
The court heard how he claimed he wanted to speak with Sharon, and planned to do this in the car while she was driving and he was in the boot.
French was found guilty of attempted kidnapping following a three-day trial at Cambridge Crown Court and on Friday, was jailed for four years.
He was also disqualified from driving for five years and his car was confiscated.
Sentencing French, the judge described him as "posing a significant risk to future partners in times of relationship breakdown", which could have "fatal consequences" and that his actions were "premeditated and sinister".
As he committed the offence while on life licence, French will not be released from prison until a parole board deems him to no longer be a threat to any member of the public.
Detective Constable Paul Atkinson, from the Domestic Abuse Investigation and Safeguarding Unit (DAISU), said: "French is an extremely dangerous individual who will spend a considerable amount of time behind bars.
"Sharon has shown great bravery in not only contacting police, but walking away from what was years of abuse - this is not an easy thing to do, and unfortunately many people, both men and women, continue to suffer in silence.
"I would encourage anyone who is in an abusive relationship to speak with someone, it doesn't have to be the police; telling just one person could be the first step to getting yourself out of the abusive situation."
PC Dave Tee, who attended the incident, said: "In over 25 years of policing, this was one of the most potentially dangerous domestic abuse related incidents that I have ever dealt with.
"From the information that I was passed, we were dealing with and looking for an extremely dangerous individual with serious intentions of causing significant, if not fatal, harm to his wife."
Anyone who is a sufferer of domestic abuse is encouraged to speak to someone, and to make contact with police.
