Angry David Colvin attacked his former partner's new boyfriend after driving his BMW convertible into the back of his car.
Colvin, 47, from Bushey, used a wheel brace to smash the side window of Paul Clark's Toyota MR2, telling him: "I am going to kill you."
When Mr Clark got out of the car in Waldegrave Park, Harpenden, he was hit by Colvin with a T bar Allen key, causing a three inch wound to the left side of his waist.
Tettah Turkson, prosecuting at St Albans crown court on Tuesday, said Mr Clark, who lives in Harpenden, was chased around his car by Colvin, before he ran off into nearby trees for shelter.
"The defendant got back in his car and drove at Mr Clark. Tyre tracks could be seen across the verge," said the prosecutor.
Julie Pearce, Colvin's ex and Mr Clark's new partner, had been in the Toyota when Colvin had smashed into it at speed. The police were called and Colvin drove off at speeds of up to 60 miles per hour. He was eventually stopped when a police car blocked his path and another came up from behind.
Colvin, of Friars Way, Bushey, appeared for sentence via a prison video link from Bedford jail, where he had been held for three weeks.
He admitted dangerous driving, causing actual bodily harm to Paul Clark, criminal damage, having an offensive weapon and failing to stop. The offences happened at 1.45pm on March 7 this year.
He did not answer police questions, but had pleaded guilty at the first opportunity, the prosecutor said.
Stephen Moore, defending, gave the judge letters from Ms Pearce and her parents Jill and John Pearce, who said he had an inability to cope with emotional issues. In the past he had made suicide attempts. They said he had depression, but his calls for help had been ignored. Ms Pearce said Colvin needed help to move on.
Mr Moore said: "He is extremely remorseful for his actions. He was driving in the area and saw the two parties together and felt himself snap. He has been seeing a counsellor about abandonment and rage."
He said he was suffering ongoing pain and stress from a back injury and had made two suicide attempts since January.
Judge John Plumstead said: "He needs help. What he did was very serious. He used a car as a weapon. He then got the Allen key from the boot of the car. It is pure luck only minor injuries were caused to his love rival. His driving put complete strangers at risk."
The judge passed a total sentence of 12 months, but said he was suspending it for two years as "an act of mercy" having read a well thought out probation report, the fact that he had sought help from a counseller and because his former partner and her parents spoke so well of him.
Colvin will be supervised for 2 years by probation officers and will have to attend an Integrated Domestic Abuse Programme. He was also banned from driving for a year.
The judge ordered that his car, which had personalised number plates, should be forfeited to the Chief Constable of Hertfordshire. After hearing that the car was now kept at Ms Pearce's house, the judge said she had seven days to request to keep it.
He also banned Colvin from contacting Mr Clark.