The All Rise hitmakers parted ways in 2005 after five years together and Costa was forced to give up his countryside home and move in with his parents after running out of cash due to his luxury lifestyle.
Costa landed a role in stage show Blood Brothers, but his small pay cheques meant he had to sleep on a friend's sofa as he could not afford to pay for transport to get him back to his parents' home.
He tells DailyMail.co.uk, "It was an odd process. I went from earning £250,000 a month on a tour to £400 a month acting in Blood Brothers.
"I wasn't saving any of my money along the way and I had champagne taste with lemonade money in the end. I thought Blue was going to last forever and any money I did have left at the end of Blue I wasn't advised on how to save it but I don't blame anyone for that."
"I lived with my mum and dad a bit at home then when I worked at Blood Brothers I couldn't afford to get home so I stayed with my mate on his sofa."
The singer decided against turning to his former bandmates for financial help, adding, "I didn't want to bother the boys as they had their own stuff going on and it was my business, I got myself into it and wanted to get myself out.
"'You have to stand on your own two feet in life no matter how tough it gets. I am not really one to ask others for help no matter what is going on, perhaps that is a weakness or just my pride but I prefer to see it as strength."
The band reunited in 2009, and is now forging a second comeback on the back of U.K. reality show The Big Reunion.
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