Jordon Harwood, a police community service officer for Northumbria Police, spent the weekend behind bars after being arrested for lashing out at his fiancee after she admitted she had been having an affair.
Perth Sheriff Court was told CCTV footage shows Harwood striking Jennifer Holland when he confronted her on Queen's Bridge in the town after getting drunk at their pre-wedding party.
Harwood, 29, of South Shields, admitted assaulting Miss Holland on 17 May. He told the court he had no idea if his wedding in a fortnight's time would now go ahead and he feared disciplinary action in his job.
Harwood was fined £400 by Sheriff Michael Fletcher.