Taking to her Instagram to share two images depicting broken hearts, the 49-year-old actress detailed the "excruciating pain" she was experiencing and confessed she still loved her husband, to whom she has been married to since 2007.
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"Nothing to say excerpt THANK YOU for all the loving and encouraging messages," she told her followers in the early hours of Friday morning.
"I never thought this would happen to us. I am still fighting against it, because I love our kids, and I still love him, but something has happened inside his head and whatever it is, I don't see him coming back to us."
The couple, who first met in 2000 while co-starring in 102 Dalmatians, are parents to two little girls, Ella Betsi, born in 2009, and Elsie Marigold, who arrived in 2013.
Alice shared these two images of broken hearts
In the candid post, Alice added: "The pain is excruciating but I am stronger than an ox, and though I weep all day when my kids aren't looking, at night I add up figures and plan futures for us and you know what? I will do those two angels right if it's all I ever do! And Emma, of course, if she PROMISES to stop jumping everybody! Your Alice xxxxx."
Fans of the star were quick to offer their words of sympathy, with one writing: "You are stronger than this trust me I have been there. You are beautiful, smart and will be happier one day soon. I promise you." Another remarked: "Don't forget to love yourself. You are worth love. You are amazing."
Alice and Ioan are parents to two little girls
Last month, Alice has revealed that Ioan made the decision to leave their family. She tweeted: "Sad news. My beloved husband / soulmate of 20 years, Ioan Gruffudd, has announced he is leaving his family, starting next week.
"Me and our young daughters are very confused and sad. We haven't been given a reason except that he 'no longer loves me'. I'm so sorry."
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