Ildico was the last person to see Attila alive. I read he died from nosebleed. I guess their men would have found suspicious to find Attila dead and with his face full of blood. Did they suspect Ildico? Had she anything to do? What was her fate?
The short answer: no.
The long answer: The Ildico story was probably an invention of Roman propaganda, recorded via a surviving fragment of Priscus. The name is a real one, so she probably actually existed, and her wedding was probably a real event that occurred. Attila had many wives, largely for political reasons, and Ildico was just another on the list.
Ironically enough, for once Jordanes is the one who is to be believed. Attila died of Cirrhosis of the liver, probably, hence the nosebleed. Whether or not it occurred on his wedding night is impossible to say for sure - that could just be embellishmen - but it's entirely possible.
Ildico probably inspired in part Kriemhild in the Niebelungenlied (The Saga of the Niebelungs), a famous Germanic epic based on this period (alongside many others). That's part of where the idea that Ildico deliberately killed him comes from, as modern authors drew that connection, but it was also a contemporary rumor floating around the empire at the time of his death.
Ian Hughes' Attila The Hun: Arch-Enemy of Rome is the most recent and up-to-date biography of Attila the Hun. But for a more comprehensive work on the Huns, I'd turn to Hyun Jin Kim's book The Huns.