In a new court petition for joint custody of their two children, the Welsh actor, 48, says he realised his marriage "was not salvageable" when he discovered Alice asleep on their kitchen floor after she allegedly began drinking at 11am one morning in July 2020.
The Fantastic Four actor claims the day before he left to travel to Australia, Alice yelled at him consistently "in the presence of the children", and claims the actress "stuck me on the head and neck".
Ioan makes the claims in his latest petition to Los Angeles Superior Court, in which he accuses his estranged wife of trying to prevent him from communicating with their two children.
Alice has denied all her ex's claims by taking to Instagram on Sunday to describe the petition as "just lie after lie after lie from my husband in order to take my kids away from me."
Setting out his reasons for splitting from Alice, Ioan writes in the court document: "In mid-July 2020, I had to return to Australia to finish a television series I was working on.
"The day before I left, Alice started drinking alcohol around 11 a.m. She yelled at me consistently throughout the day that I was a "p***y," and that everyone in the industry hated me.
"In the presence of the children, Alice screamed that my family is disappointing and my mother never had her back."
He continued: "Alice also struck me on the head and neck. Later that night, I found Alice asleep on the kitchen floor.
"That incident was the final straw that made me realize our marriage was not salvageable."
Ioan filed for joint custody of the former couple's two daughters Elsie, 8, and Ella, 12, on Friday, months after the actress applied for sole custody amid their bitter split.
Taking to Instagram on Sunday, the mum-of-two reacted to her estranged husband's joint custody request and published a trio of screenshots of alleged emails and texts from Ioan to herself and their eldest daughter.
In the request filed in Los Angeles Superior Court earlier this month, Ioan also petitioned for his two children to attend in-person therapy and reunification therapy with him pending court-ordered mediation about custody.
Filming herself reading a physical copy of the petition on Sunday, Alice can be heard telling her 85,200 Instagram followers: "It's basically just lie after lie after lie from my husband in order to take my kids away from me."
Alice broke down in tears as she flicked through the latest court document in which Ioan reiterates his previous claims that she verbally abused him throughout their marriage.
"I've just started to read this declaration from Ioan. It is utterly disgusting and absolutely packed with lies, saying that he was the major caregiver and that I would get up at 11am and drink," she tells her fans as she films.
"That's just not true, just absolutely not true. I've looked after these girls every day of their lives since they were born. I think I've been away like nine nights.
Alice and Ioan initially announced their split in January 2021 and have been embroiled in a bitter divorce row ever since.
The Titanic actor went public with his current partner Bianca Wallace in October 2021, after striking up a romance with the Australian actress in June the same year.
The actor filed a restraining order against his estranged wife back in February.
He requested Alice should have to stay 100 yards away from himself and his girlfriend Bianca Wallace, and that she should not be able to contact them.
In the court documents signed on Tuesday 14 February 2022, Alice has rejected all of Ioan's claims and accused him of filing the request as "a ploy to gain some sort of advantage" over her in the upcoming divorce proceedings.