Mark Oliver, 51, of Cheltenham Way, punched his girlfriend to the floor with a single punch to the right side of her face after being told she was leaving him.
In a statement which was read out in court, the woman described how Oliver “went mad” after her phone beeped.
Lincoln Crown Court heard the woman fell to the floor after being struck to the face in their caravan and was then punched a further five times.
In her statement, the victim said she told Oliver to “watch her bones” as she was repeatedly punched to the face while lying on the ground.
She said: “He use to box and I felt he was punching me with full force.”
Police were called and injury photographs showed the woman suffered two black eyes, scratches, swelling to her nose, and an injury to her ear.
The court heard the couple had been living in a static caravan in Mablethorpe.
In her statement, the woman described Oliver as “unpredictable, violent and controlling.”
Oliver denied an offence of assault causing actual bodily harm to his partner on October 6 - but was convicted after a trial at Lincoln Magistrates’ Court.
In mitigation, the court was told Oliver now accepted the court’s verdict.
Passing sentence, Recorder Patrick Upward QC told Oliver his victim had suffered serious injuries.
The Recorder added: “Men who batter women need to know they are going to custody.”