The report says 48-year-old Dennan Crosby began taking anti-depressants after he broke up with the woman but refused to follow his counsellor's advice to go to the hospital in May 2012.
The following day, Crosby showed up at his ex-girlfriend's house with explosives and took her hostage while her four kids and boyfriend escaped.
The report says that during a seven-hour standoff with the RCMP, Crosby revealed he began making bombs and testing them several weeks earlier and that he'd travelled from his home in Surrey to Kamloops about 15 times.
Crosby eventually let the woman go and set off an explosion that destroyed the house and killed him.
The coroners service says anxiety contributed to his death, which has been deemed a suicide. (CHNL)