Speaking after the verdict was read out. Kristopher Mulder (19), the couple's second-eldest son, said that "justice had been done". The teenager said he was "glad his father was going to prison for life". He described his mother as a "kind-hearted, easy-going, soft and intelligent person".
"She was my mum and I loved her," he added. He expressed his hope that his family could try and move on, and try and put this terrible and tragic event behind them.
At present, Colleen Mulder's mother, Patricia Ferreira, in Bangor, is caring for his younger sisters.
The victim's sister, Ann Czerepowicz, said she was "over the moon and absolutely delighted" with the guilty verdict.
She admitted it was unexpected. There were a lot of difficulties within the marriage, which she did not want to go into.
Ms Czerepowicz felt there were a lot of things that did not go before the jury that would have re-enforced the case against Anton Mulder.
She added not a day goes by when the family don't think and talk of Colleen.
Ms Mulder's brother, William Carson Pollock, excluded from the court after making an inappropriate approach to a juror, welcomed the verdict. He said he was thrilled.
"Anton Mulder got what he deserved after what he put my sister through."