The Reservoir Dogs star said he "can't stand another minute in the house" with the Loose Women star, claiming she is "emotionally disturbed".
After last night's face-to-face nominations, Frankie Cocozza, Natalie Cassidy and Nicola McLean rallied around an upset Welch.
Cocozza said: "That was still so evil - I can't even get over that," while Cassidy vowed not to speak to Madsen again.
The former EastEnders star added: "I will not be entertaining conversations, because I don't like false people.
"I can't let it lie... He needs to be told that it was wrong what he said to Denise."
Gareth Thomas, who defended Madsen's integrity while nominating him, admitted that he would like to leave the house.
Yesterday in a shock twist, Big Brother revealed that all housemates apart from Thomas are up for tomorrow night's eviction.
> Denise Welch is 'crumbling' in Celebrity Big Brother, says Georgia Salpa
> Michael Madsen, Denise Welch's Celeb Big Brother truce ends abruptly
Watch the face-to-face Celebrity Big Brother nominations below: