The actress – who has been married to Ioan since 2007 and shares two children with him – shared a screenshot of a media story about the end of her marriage, and wrote: "Oh. OK. Thanks for letting me know. I guess?" along with an upset emoji.
She then responded to a number of well-wishers in the comments section, giving further insight into her heartbreak. "Is there any need for him to be so cruel?" one fan wrote. "I'm so sorry x." "Thank you," Alice replied. "I still have no answers. Wish I did!"
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In another lengthy message to someone who questioned whether she was truly blindsided, she added: "When does one ever know? Don't you still hope as long as hope is there? I thought we were in this together and would announce together.
"It's ok to be shocked. It's ok to share that I'm shocked. That I'm hurt. Nobody had to read it. But there are some that might want to know. And others who might feel a teeny bit better about the painful things that have been done to them. Peace."
Alice shocked fans when she announced the couple's split in January
Alice, 49, stunned fans in January by announcing that Ioan had decided to leave their family. She wrote: "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."
The former couple are parents to two daughters
Liar actor Ioan, 47, and Alice first met in 2000 while co-starring in 102 Dalmatians, and went on to tie the knot seven years later, in September 2007.
The couple got engaged on New Year's Day in 2006, with Ioan revealing that Alice had given him an ultimatum. "Alice has been very patient with my procrastinating with my male ways," Ioan later said. "She did give me somewhat of an ultimatum - a gentle nudge - which was the best thing she could do really."
The couple are parents to two little girls, Ella Betsi, born in 2009, and Elsie Marigold, who arrived in 2013.
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