A former kickboxer and serial stalker has been jailed for 28 months after harassing his ex-girlfriend and threatening to smash her late husband's gravestone.

The ACT Supreme Court heard 47-year-old Ian Murray's repeated attempts to contact his ex-partner were menacing and disturbing but the man showed little remorse and claimed the victim was psychologically unstable.

The Queanbeyan man had hoped to walk free after spending nearly 17 months in custody awaiting his day in court but will stay behind bars until August.

Handing down her sentence yesterday, Justice Hilary Penfold said Murray seemed to believe he had a continuing right to contact his former partners and control their behaviour.

The court heard Murray and the victim had a brief relationship in late 2009 but it ended in 2010 when she reconciled with her estranged husband, who had been diagnosed with cancer, and cared for him until his death later that year.

The woman took out a protection order against Murray but he continued to ring her repeatedly, inviting her and her daughter to a kickboxing match in Civic and dropping by her house with a 1.5-metre gardening tool.

When the woman refused to take his calls, Murray threatened to desecrate her husband's grave, saying: ''If you ever, ever, ever hang up on me again I am going to go out and smash that filthy junkie's headstone. This has gone far enough. You and I will be talking.''

The court heard the woman was terrified of Murray and of what he would do to her family. The former scaffolder was arrested in December 2010 and has been in custody ever since.

He was due to stand trial this year on four counts of breaching protection orders but pleaded guilty in March.

Justice Penfold said Murray had 20 previous convictions for breaching protection orders, stalking and attempting to intimidate others and had been jailed in other states.

But the court heard the man had no signs of mental illness.

In a letter to the court, Murray said the relationship was intense and he was caught by surprise when his ex-girlfriend took out the protection order, believing she was still affected by her husband's death.

He blamed the victim for being psychologically unstable and said he would be more careful to see the ''warning signs'' when he chose future partners.

Justice Penfold described the letter as nonsense.

She said Murray revealed a ''fundamental lack of insight and a misconception about relationships''.

But she also noted that he hoped to get his life back on track when he was released from prison and had offers of a place to stay and a job.

Justice Penfold sentenced Murray to a total of 28 months' jail, backdated to December 2010.

Murray will be eligible for parole in August and will be subject to a good-behaviour order for two years.

The judge warned him that both parties in a relationship had the right to withdraw and refuse contact.

''If you don't come to grips with that basic fact, Mr Murray, I can see you coming before the courts again and spending increasing amounts of time behind bars,'' she said.