Jamie Lynn Spears was reduced to tears while discussing the rift with her famous sister Britney during a new interview on Good Morning America.
The pair have what Jamie Lynn describes as a "complicated relationship" - which has seen both of them publicly hit out at the other on social media.
In a new clip, the former child star is questioned about her strained relationship with the singer. In November, a judge put an end to the conservatorship that has controlled the singer's personal, professional and financial matters since 2008.
Her father Jamie Spears - who was also her conservator - pointed to her public mental health struggles as justification for the legal guardianship, and what was intended as a temporary arrangement was made permanent by the end of that year.
Jamie Lynn's new interview coincides with the release of Jamie Lynn’s memoir, Things I Should Have Said. GMA shared a clip of the interview ahead of it airing on the network on Wednesday, January 12.
"I love my sister," Jamie Lynn is heard saying, before presenter Juju Chang asks: "But things have gotten complicated?"
"I guess so," Jamie Lynn replies. She is asked about what "cause the rift" between the sisters and what she "regrets".
Britney unfollowed her sister on Instagram earlier this month. The rift between the siblings became public during the final months of Spears’s legal battle to end her long-standing conservatorship.
In June last year, Spears broke her silence on the conservatorship in a court testimony during which she called for her father and others involved in the legal arrangement "to be in jail".
Following her appearance at open court in Los Angeles, the singer wrote a lengthy message to fans in which she complained about people close to her "never showing up".
The message came shortly after Jamie Lynn had publicly pledged her support for Spears for the first time. In July, however, Spears called out her sister specifically.
"I don’t like that my sister showed up at an awards show and performed MY SONGS to remixes!" she wrote at the time. "My so-called support system hurt me deeply!"
"If you’re like my family who says things like ‘sorry, you’re in a conservatorship’ ... probably thinking you’re different so they can f*** with you," she added.
Spears's mother, Lynne, has previously defended Jamie Lynn, telling critics to "stop" attacking her youngest daughter.