The Tragic End of Karl Marx's Daughter

Here's a paragraph from Andrew Marr's The Making of Modern Britain that packs more intrigue and tragedy than most novels. And, it's true.
"... Eleanor Marx, daughter of Karl. She had nursed him, helped finish Das Kapital and then thrown herself into socialist politics. She lived with Edward Aveling, another socialist, in what the Victorians would call 'sin.' Aveling married an actress without telling Eleanor and then proposed a joint suicide pact, leaving her with the prussic acid. Eleanor killed herself while he quietly left, very much alive. Which was a sin."