CEO of Mt. Gox, Mark Karpeles, has finally broken his silence to tell the world how it feels to lose 850,000 bitcoins.

In an exclusive interview with the Wall Street Journal’s Tokyo reporters Takashi Mochizuki and Eleanor Warnock, Karpeles revealed he was "scared, frustrated and angry" in February when he realized the extent of the now-defunct exchange's losses, which total $499,027,945 at today's exchange rate.

He lamented that as the head of the company, it had been his mission to protect customers and employees, admitting that "The weakest point of my company was management," for failing to lay out appropriate corporate structures or hire experienced executives.

Karpeles also admitted the company grew too fast for him to handle, something often suggested by both supporters and enemies alike.

Many of Mt. Gox's former customers and staff will no doubt be pleased to hear these confessions in the absence of any other compensation. Karpeles believes now that aside from the 200,000 BTC subsequently recovered, no further bitcoins will be found.

He does plan to auction off his domain name assets in one attempt to return some funds, including bitcoins.com and akb.com (a popular name in Japan thanks to pop group AKB48).

Karpeles now lives alone with his cat in his upmarket apartment in the south-west of central Tokyo, where he still operates his web services company Tibanne.

Responding to accusations from angry creditors that his lifestyle choices remain extravagant, Karpeles said:

The CEO added that he would like to attend Tokyo's weekly bitcoin meetup "when things settle down" to explain the course of events to users in his own words.

According to the WSJ report, he has also had many sleepless nights, always worried about the fate of Gox's bitcoins and apparently himself:

As well as the hacking attack that saw 850,000 BTC vanish, there had also been physical break-ins at the office and one former employee stands accused of stealing sensitive data.

Karpeles is still officially the CEO of Mt. Gox, though he no longer has any control over the company's remaining funds and a police investigation into what happened is ongoing.

There are at least two competing groups trying to take control of Mt. Gox with differing plans for reactivating the company and attempting to make creditors whole: Sunlot Holdings' SaveGox, and a team of Tokyo locals supported by Chinese exchange OKCoin.

Karpeles said he supported a rescue plan, but added that whatever customer funds remained should not be touched, "Any buyers should use their own money to rehabilitate the exchange, not Mt. Gox’s."

When asked if he regretted buying the exchange, the CEO mused, "Half-yes. I learned a lot, but I lost a lot."

Co-authored by Jon Southurst and Grace Caffyn