Once boasting one of the closest friendships on the circuit - Riesch's family used to host Vonn regularly during the festive season - the pair's relationship has turned sour in the wake of Riesch ending Vonn's stranglehold on the World Cup title.
"I stopped talking to Maria after the first leg of the slalom at Spindleruv (Czech Republic on March 11-12)," Vonn, who had won the title the three previous seasons, wrote on her Facebook page on Saturday.
"She had given a series of negative interviews about me and has since continued to talk in a negative fashion about me. I am very hurt by her actions and I honestly don't know where our friendship stands at this point."
Vonn did not attend Riesch's wedding on April 14, justifying her no-show by claiming both she and her husband Thomas had not been made to feel welcome. After returning from their honeymoon, Riesch's new husband Marcus Höfl hit back at Vonn's allegations.
"We have discussed whether one should react to this at all," Höfl told the Thursday edition of Munich newspaper TZ. "Now, it's just getting ridiculous. But on the other hand, Lindsey is lying again and we can't just leave that unchallenged.
"She is trying to make out the whole thing is a cat-fight and that Maria is a bitch. She is just getting caught up more and more in their lies."
Höfl insists Riesch has never said anything negative about Vonn.
"They should substantiate what they are saying," said the German. "They can't, because it is simply not true. Lindsey says she personally congratulated Maria (after winning her title), which is not true. To date, neither she, nor her representatives, have ever done that."
Höfl questioned whether the pair, both 26, had even been genuine friends.
"The question is, was this ever a real friendship or was it just Lindsey was okay about things as long as she was ahead of Maria?," he asked. "In any case, what she has done has become ridiculous."