A German woman has been sentenced to 12 and a half years in prison for selling her young son on the darknet to abusers, in a case that has horrified the country and raised questions about its child protection services.

The 48-year-old woman and her partner, 39, a convicted paedophile, were convicted of forced prostitution, rape, sexual and physical abuse, humiliation, and bondage in almost 60 separate identified acts.

The partner was given a 12-year prison sentence plus a preventative detention order, which will effectively keep him in prison for life. Six other men, including a Spanish man, a Swiss citizen and three German men who had paid the couple to abuse the boy, now 10, were given sentences of between eight and 10 years.

The court in the south-western city of Freiburg heard that the abuse had been going on for two years. The mother had threatened her son with foster care if he reported it.

The paedophile ring was operated like a business from the town of Staufen, near Freiburg, where the couple lived. Abusers were believed to have paid up to €10,000 (£8,950) a time to abuse the boy.

The couple, identified only as Berrin T and Christian L, admitted to the court that they had sold the boy to numerous men and that they had abused him themselves. They received slightly reduced sentences for passing information to investigators, enabling them to pursue other perpetrators.

Others on trial included a 44-year-old German who was given access to rape the boy but was prevented by the mother from carrying out his wish to kill him.

The court heard that videos made of the abuse were sold for large sums via the darknet, an area of the internet that can be visited only by using special software. Police exposed the ring last September after an anonymous tip-off.

The judge Stefan Bürgelin said the boy’s mother had initially been motivated to take part in the abuse in order to ensure that Christian L did not go through with his threats to leave her. Subsequently it was financial incentives, Bürgelin said.

The shocking details of the case – the worst of its kind in German criminal history – have triggered calls for an overhaul of Germany’s child welfare facilities. Questions have been asked as to why no welfare officer picked up on the boy’s plight, and why no attempt was made to prevent him from living under the same roof as a convicted paedophile.

Wilhelm Rörig, a government-appointed envoy for abused minors, said a string of bureaucratic failures that enabled abuse of the boy to continue for so long were inexcusable and would have to be “unsparingly examined”.

He said the case highlighted flaws in the family courts system, and he suggested family judges should in future receive more legal training in the sexual abuse of minors. He also called for more funding for youth services.