The ex-husband of a former teacher accused of having sex with one of her students in Vernon, B.C., has told a court his marriage was crumbling about the time of the alleged affair, a local report says.

Mike Jellema testified Friday in the trial of Deborah Ashton, who has pleaded not guilty to five sex-related charges involving a former Grade 7 student dating back to 2002 when the boy was 12 years old.

Jellema said he had no intimacy with Ashton about that time, but noticed she began wearing thong underwear and he found condoms in their bathroom, radio CKIZ reported.

He also said he was suspicious of all the time Ashton spent away from home, but when he asked her about it, she said it was none of his business.

He said she spent more time with students than with him and their family.

Defence lawyer Terry La Liberte objected to the testimony, saying the marital problems had nothing to do with the case and the Crown's line of questioning was "total nonsense."

Jellema also denied threatening to write an anonymous letter that would "destroy her."

The alleged victim, who is now 22, testified for the first three days of the trial, which is expected to conclude about March 16.

This is Ashton's second trial on the charges after the first ended in 2011 in a hung jury.

With files from the CBC's Brady Strachan