Deianira's own struggle with the chthonic forces was not over. Later, a wild centaur named Nessus attempted to kidnap Deianira as he was ferrying her across the river Evenus, but she was rescued by Heracles, who shot the centaur with a poisoned arrow. As he lay dying, Nessus lied to Deianira, telling her that a mixture of the semen that he had dropped on the ground and his heart's blood would always ensure that Heracles would love her forever. Deianira believed his words and kept a little of the potion by her. Heracles fathered illegitimate children all across Greece. When she became uncertain if Heracles would remain true to her in his fashion, Deianira smeared some of the blood on Heracles' famous hide shirt. Heracles' servant, Lichas, brought him the shirt and he put it on. The centaur's toxic blood killed Heracles. In despair, Deianira committed suicide.
Reference
Harry Thurston Peck, Harper's Dictionary of Classical Antiquities, 1898.