The bitter bass player quit the band in 2007, telling the media they had split up - but his three ex-bandmates stayed together and are currently touring with a new member.
Tired of all the remarks Hook has made about him in the media in recent years, Sumner has decided to break his silence over the feud in an exclusive interview with Spinner.com.
And he admits things have not been good between him and the bassist for over a decade, after Hook returned to the band following a spell in treatment for alcoholism.
Sumner explains, "When he came out of treatment for this event, he was a worse person, in my opinion... He tore strips off me and said everything that had ever gone wrong with New Order was my fault; everyone was really puzzled... And then he just started attacking everyone else - the management - everyone was 's**t' except him."
The singer admits Hook's former bandmates were also upset by the bassist's business dealings and his apparent lack of interest in New Order.
Sumner adds, "He'd rubbed us all up the wrong way by buying the name of the Hacienda club (in Manchester)... We'd all put a lot of money each (into the club); when it went bust, he bought the name, we felt, behind our backs, and he started selling it for various uses, like there's an apartment block there now where it was, and he sold a licence to the developers to build it. That was when we'd just got back together in 2001. So we lost respect for him and trust after that.
"We did a tour of South America, in which he was a very angry man, and he got really into the celebrity Dj circuit. We did the music for (the Ian Curtis biopic) Control, and (director) Anton (Corbijn) wanted ambient, quiet music. I said (to Hook), 'If you want to play on it, you're quite welcome'. (He said), 'Can't do that, I'm Dj-ing'.
"We were supposed to be completing an album, which is now known as the Lost Sirens - seven tracks; we were going to write another three and we'd have a finished album: 'Can't do it. I'm Dj-ing'.
"Then he announced, without discussing it with the band, that we'd split up, and suddenly it was news all around the world. And he did it just before the Cannes Film Festival, so every question was not about Anton's film; it was about New Order splitting up. We released a press statement saying, 'New Order haven't split up. It's a unilateral decision by Peter Hook.' And we haven't split up. New Order continue. So, to us, he left, but didn't want to say, 'I'm leaving'."