A Manhattan woman who claims she had a years-long affair with married multi-millionaire Robert Rosenkranz confronted his wife on social media with a handwritten note from their mutual love. 
 
 Katherine Nelson alleges that Rosenkranz, 72, CEO of the $10 billion Delphi Financial Group and a member of the Council on Foreign Relations, duped her into signing a gag order in May regarding their four-year-long affair. 
 
 By August, Nelson was ready to kiss and tell — posting online a photo of cream-colored stationery stamped with Rosenkranz’s name with a handwritten message: “For me, two is a remarkable number.” 
 
 She then tweeted the image to Rosenkranz’s stunning 57-year-old wife, Alexandra Munroe, with the words: “You must have known.” 
 
 Munroe, a Guggenheim curator, must have gotten the message — four days later she replied to Nelson with a blank tweet. 
 
 The blonde, pillow-lipped Nelson claims in a Manhattan Supreme Court lawsuit filed Friday that she and Rosenkranz, a Yale-educated philanthropist on the board of the Manhattan Institute think tank, met at a 2010 awards dinner and launched their affair with a steamy rendezvous at the Beverly Hills Hotel, according to court papers. 
 
 The two “exchanged several hundred e-mails over a period of approximately four years with topics ranging from a private sexual nature to politics, literature and finance,” court papers said. 
 
 Nelson and Rosenkranz exchanged “romantic presents from Tiffany, Hermes and Paul Stuart,” and he even introduced her as his wife at a meeting of Yale trustees, the filing alleges. 
 
 Nelson claims Rosenkranz persuaded her to sign the confidentiality agreement by promising her $100,000 and assuring her “it would not affect their relationship.” 
 
 Nelson says she signed it without a lawyer — and never got paid. 
 
 The two kept up “intimate relations” at Rosenkranz’s Manhattan office and in Aspen, before Nelson spotted him out with another woman at BLT Steakhouse, according to the lawsuit. 
 
 When a weeping Nelson confronted her alleged lover, he pretended not to know her. Later, when Nelson told Rosenkranz she was writing a book, he “reached for [her] throat,” she claims in court papers. 
 
 She’s asking a judge to void the agreement. Rosenkranz has not returned messages for comment. 

 Another salacious legal document is turning heads in the financial community. 
 
 Fresh off the Sage Kelly divorce drama at Jefferies, Delphi Financial Group founder and CEO Robert Rosenkranz is being accused by an alleged mistress of promising her $100,000 to not talk, according to a lawsuit citing by various media outlets. 
 
 The accuser, Katherine Nelson, appears to have taunted Rosenkranz's wife Alexandra Munroe about the affair in a tweet. 

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– A woman who claims she was a millionaire's mistress has slapped him with a lawsuit and sent his wife a nasty little tweet, the New York Post reports via CNBC. Katherine Nelson (described by the Post as "blonde" and "pillow-lipped") is suing 72-year-old Robert Rosenkranz, a member of the Council of Foreign Relations and head of the Delphi Financial Group, alleging that he coerced her into signing a gag order about their 4-year affair without explaining what the papers were about. Nelson also tweeted Rosenkranz's wife, 57-year-old Alexandra Munroe, an image of a handwritten message on his business card: "For me, two is a remarkable number." Nelson's tweet: "You must have known." Munroe sent back a blank tweet, suggesting she got the message. According to the lawsuit, Nelson met the Yale-educated philanthropist at an awards dinner in 2010. They allegedly kicked off their affair at the Beverly Hills Hotel and "exchanged several hundred e-mails over a period of approximately four years with topics ranging from a private sexual nature to politics, literature and finance," the suit says. At one point he duped her into signing a $100,000 "money-for-sex" agreement, according to the suit; the Post says he never paid up and the Daily News reports that she received a check but was insulted and shocked. They broke up in September after Nelson allegedly spotted him at a restaurant with another woman and broke down crying. She threatened to write a book about the affair, the suit claims, and "in a moment of aberration, he reached for defendant’s throat." No word yet from Rosenkranz.