The former Dancing on Ice contestant confirmed that she separated from builder Steve Toms on Boxing Day last year, after a two-year union. The couple got together in 2003, embarking on an affair towards the end of McLean's marriage to first husband Nick Green.
42-year-old McLean - mother to 10-year-old Finlay and 5-year-old Amy - insisted that she had tried hard to give her children a happy home, but soon felt "completely destroyed" by her new relationship.
"I'm still in shock. When I hear myself talking about 'my first marriage breakdown' then 'this time round', the words are like a stab in the heart," she told The Mirror.
"I feel I have let my children down. They don't deserve this. I just wanted to give them what I had - a happy, loving home with a mum and dad who adored each other. And all I've ever wanted is to be one half of a couple. But now that's all gone. I'm heartbroken.
"I hated myself for a long time because of [the affair]. Then, six years later when Steve and I finally got married, I went into it with a heart full of love and hope - determined this would be different.
"But as time went by and I realised I couldn't make this marriage work either, I felt utter panic. I feel completely destroyed by it all."
McLean said that she had accepted after the split that "life comes with bumps and grazes", thanks to the support she received from her Loose Women co-star Sherrie Hewson.
"On my first show of the New Year, the topic was, 'Why do marriages break down at Christmas'," she recalled. "I just wanted to burst out crying, but somehow I got through.
"I'd kept my marriage problems to myself and only Sherrie Hewson saw through my brave face... She said, 'You're young, beautiful and a lovely person and you deserve to be happy - so if you're not happy about anything in your life, please don't wait'.
"I really thought about what she said. It reinforced what I knew deep down. I had to move on."
McLean declared while stripping off for a magazine shoot in November that she was going to "throw caution to the wind" from now on in her life.
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