Lee Greasley and Faye Stansfield, who had been together for nine months, went out separately on New Year’s Eve.
Becky Mahon, prosecuting, said he phoned her repeatedly that night and that they had an argument in the centre of Clowne when he grabbed her wrist.
Ms Stansfield went into pub toilets and Greasley, 35, followed the mother-of-two inside in an aggressive mood.
Back at her home in Northfields, Clowne, he tried to throw her out of bed and threatened to throw her out of a window.
Greasley, of King Street, Clowne, admitted assault and causing £200 damage to property on 1st January. He had a previous conviction for a drugs offence.
Magistrates adjourned sentence until 6th February for probation service reports and granted bail on condition he did not contact Ms Stansfield or go to her address.
“He is very remorseful. He doesn’t seek to provide any excuses. He was upset, knowing the relationship was coming to an end. He felt unwanted and he became frustrated,” said Denney Lau, for Greasley.