ROME – Opera diva Maria Callas’s private letters, written in the dying days of her love affair with Aristotle Onassis, will be auctioned in Rome today and international interest in the sale is high. The half-dozen missives, sent to her voice teacher Elvira De Hidalgo and written in the late 1960s, unmask a desire for revenge against Onassis and Jacqueline Kennedy, the woman he would marry, saying they both deserved to suffer. Callas, depressed and unfulfilled, was to die alone in Paris in September 1977, aged 53. Onassis died in March 1975. Auctioneer Christie’s will put a total of 11 Callas lots of letters and photographs under the hammer with a reserve price of more than $15,000. Penned as her nine-year affair with Onassis was collapsing, Callas’s letters also touched on the disillusion she felt and her battle to lose weight, while revealing the anger and twisted mood swings of the tormented star. «It’s cruel, it isn’t true – both should pay; and both will pay, you’ll see,» she wrote in late October 1969, days after the elderly shipping tycoon and the slim, chic widow of assassinated US President John F. Kennedy, were married. «The worst thing is that he didn’t say anything to me about the marriage. After I’d spent nine years at his side, I think he was obliged to do that – or at least not to let me learn about it in the papers. «But I think he’s crazy and, as such, I’m going to wipe him out of my mind, and I shall try to do it as soon as I can.» In June of the same year, as the relationship between Onassis and the former first lady was blooming, the singer wrote to De Hidalgo: «I’m doing all right under the circumstances, but it’s like I’ve been given a huge smack and I can’t breathe any longer. I’ve received three telephone calls (from Onassis). One I didn’t take – the other two I did and it was a disaster. «As I told you, he’s lost it and that’s something that’s really horrible for me to accept. I’m in Paris and I’m going to try to put a little order in my oh-so-painful head.» she wrote. While their affair continued after the marriage, it was to prove the most humiliating period of Callas’s tragic life. And even as she struggled to hold on to her lover, the woman whom film director Franco Zeffirelli dubbed the «high priestess of opera» was fighting to retain her divine voice. «I’m rebuilding everything,» she wrote to De Hidalgo in January 1968, as she worked alone on new singing methods. «Let’s see what happens. In any case, things weren’t right before. So, I haven’t got anything to lose at this point. If it works, it works – otherwise, I give up.» Haunted by the treachery of a man who once gave her a $1-million diamond ring and battling depression, Callas was in a reflective mood as she sent De Hidalgo news in April 1969. «Pretty soon I will have to start writing my biography and I’ll need a few memories and things from you… I’m better – I feel more secure. I’m a little fatter and feel very optimistic.» She died alone eight years later.