Jon Cryer starred opposite Charlie Sheen for seven seasons before the Two and a Half Men star's now-infamous meltdown. In an excerpt from Cryer's new memoir, So That Happened, obtained by The Hollywood Reporter, Cryer recalls the disturbing and sad details of watching his friend hit rock bottom.

When Two and a Half Men began, Cryer recalls being surprised by how normal Sheen seemed compared to his boisterous reputation. During a trip to Vegas, Sheen allegedly slept the whole time. However, when Sheen's marriage to Denise Richards dissolved during the second season, Cryer began to see the Sheen the media has come to expect. "We'd have conversations, and he'd mention that things were going well for him romantically. 'Romantically' is my choice of words, not his," Cryer wrote. "Then, as if to prove this, he'd show me a picture he'd taken of somebody's vagina. It was always a perfectly nice-looking vagina, but I would invariably think, 'Why just this, and not the rest of the person?"

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Fast-forward a few years to Christmas Day 2009, when Sheen was arrested for spousal battery of his third wife Brook Mueller. Cryer immediately reached out to his co-star, who seemed to be in surprisingly good spirits, and Sheen's manager requested that Cryer offer a public statement of support. "I told him I would be happy to but that it sounded like Charlie wasn't sober anymore, and I hoped he'd get on track again," Cryer said. "Situations like this are rough on your sense of friendship and loyalty, because the allegations are serious, yet you know Charlie and Brooke are a drug-troubled pair, and Charlie's your longtime friend who was proud of his sobriety, but that doesn't mean he didn't do something to her, and you should give a woman the benefit of the doubt when she's been abused, and oh, boy..."

In February, Sheen entered rehab and even managed to secure a raise to $1.8 million an episode, three times what Cryer was being paid at the time. However, when he returned for Season 8 in 2010 it was clear that Sheen was not well. In addition to looking "gaunt" and "sallow," his acting began to suffer. ("Charlie just wasn't hitting the jokes the way he used to," Cryer wrote.) After a few more months of this, the studio had had enough. In January 2011, Sheen was told that he was going to meet with Warner Bros. bosses Bruce Rosenblum and Peter Roth after that week's Friday taping.

Sheen didn't take the news well and began "to get manic" backstage. "Things didn't start smoothly once the show began. We did a scene with the two of us sitting on a couch, and Charlie screwed up every line," he wrote. "He could not remember anything he was supposed to say. It was hard to comprehend what I was seeing because Charlie had always prided himself on getting it done on show night. It was like watching HAL go haywire in 2001: A Space Odyssey."

Sheen eventually made it through the scene, but left immediately after the taping, without even bothering to remove his makeup. "And with that, we all accepted that something was truly broken here, that Charlie couldn't be counted on to even go through the motions anymore. That was the last episode of Two and a Half Men Charlie would ever shoot," Cryer said.

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Sheen's firing inspired the "bellicose underbelly of the Internet" to be unleashed, Cryer recalled, noting that many felt his dismissal was unfair and began lashing out at himself and creator Chuck Lorre. "An astounding number of people stood up for Charlie, as though people should be able to show up to work rarely, if at all, verbally abuse their co-workers publicly with anti-Semitic slurs, get arrested on a regular basis — as well as abuse drugs to the point where they can barely function — and not have their high-paying jobs threatened.

"A curious phenomenon was bubbling up in the media as well. Entertainment culture had become so stultifyingly repetitive and predictable that Charlie's antics felt like a breath of fresh air. To some authors, commentators and bloggers — seemingly intelligent people — he was a rebel, a truth teller willing to poke his masters in the eye. ... Of course, Charlie wasn't those things. He was simply lashing out at the people who told him the party was over. That he was actually just a human being with a monumental drug dependency mattered less to the pundits than his value as something to write about to alleviate their collective boredom. The fact that he could very well be dead soon was not their concern. In fact, it'd just give them more to write about.

"Charlie was never an insurrectionary guerrilla fighting the established order," Cryer continued. "He was a guy who got everything he had ever wanted from it. He even texted somebody at the show once, 'I think they gave the wrong guy too much money.'"