The man - who cannot be identified - pleaded guilty in the Supreme Court in Launceston this week to aggravated sexual assault.

The couple was in a relationship at the time and were engaging in consensual sex when the man inserted the handle of a baton followed by an icy pole into the woman, without consent.

The action - and further degrading acts - caused the woman pain and she ran away upset before ending the relationship and making a statement to police two months later.

The matter was due to go to trial, but further evidence from the victim prompted the man to plead guilty.

Other Launceston court news:

In a victim impact statement, the victim outlined both the immediate and long-term impact of the sexual assault.

"Straight after the event I felt dirty and humiliated," her statement read.

"I broke down and cried for hours.

"Since it happened I have the same recurring nightmare where I relive what happened that night.

"I had to move house because I couldn't be reminded of it anymore.

"I had to leave the house I lived in for 11 years."

The victim has also had to change her work arrangements to ensure she is no longer left in situations where she is alone with men.

"I built up a wall because I think all men are the same," she wrote.

The court heard the man would drink regularly which heightened his aggression and caused him to punch and headbutt walls.

He also regularly used the drug ice intravenously.

A pre-sentence report must be completed before the man can be sentenced.

He has been in custody since June.

The man will be sentenced in the Supreme Court in Launceston on April 5.

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