George Stocks, of Gypsy Lane, Old Whittington, decided to speak with his ex-girlfriend in person following the breakup.
She asked the 21-year-old to leave and confirmed their relationship was over – but he refused to go and hit her, causing her to fall to the floor.
Another man noticed the pair talking and that the woman seemed distressed.
He then also asked Stocks to leave her alone and said he would call the police.
Stocks then assaulted the man before he finally left.
The woman suffered a fractured cheek and eye.
The man suffered a cut to his head.
They both received medical treatment.
Stocks was jailed for a total of 18 months for one count of causing grievous bodily harm and one count of causing actual bodily harm.
He was also handed a restraining order, which lasts until further notice, to protect the victim from further conduct which amounts to harassment or fear of violence.
The sentence was passed during hearing at Derby Crown Court.
Detective Constable Andy Brooks, of Derbyshire Constabulary, said: “Domestic abuse is never acceptable and we continue to work hard to bring offenders to justice.
“By raising awareness of this case, we hope to encourage others people who may be suffering in an abusive relationship to seek help.”
People can report domestic abuse, which can include harassment, via www.derbyshire.police.uk/reportdomesticabuse or by calling 101 or, in an emergency, 999.