The news about Diggory is indeed grim, though he's alive. And he's been transfered to St Mungo's, though his immediate care was given here at Tilda's. Antonin Dolohov brought him through the Floo suffering circulatory collapse, the result of a Dark curse.

I'm afraid I can add little to what the Weasley twins shared with us in the journals: that there was an intruder in Madam Umbridge's office, that there were curses thrown, that Diggory was hit.

I would say that the curse used against Diggory was not the sort of thing I'd expect Dolores Umbridge to have cast on a student, though I can hardly guess what she might attempt against an intruder. With students, however, her inclination was to cause pain that could be aggravated or escalated with repeated application. In short, she far preferred sustained torture to lethal measures. The Sanguis Predonis curse straightforwardly intends to kill, but without any of the agony that she revelled in. Mr Diggory quietly fainted, and it was mere luck that Dolohov arrived on the scene to recognise the nature of his condition.

As for Madam Umbridge, I thought I understood Fred and George Weasley were claiming she's been transfigured into a toad and made into a decorative plate. Did you not see their exchange with Alice and Pomona?