Hayden Panettiere's Ex Brian Hickerson Talks Relationship Months Before Her Death

Hayden Panettiere's on-again, off-again boyfriend Brian Hickerson told us she was the textbook "Sunday girl" when we last talked to him ... and three months later she was found dead on a Sunday in an apartment linked to him.

Brian sat down with TMZ's Charlie Neff back in May -- Hayden had a new memoir out at the time -- and it's interesting to look back at the conversation in the wake of Hayden's sudden death.

Hayden and Brian started dating in 2018, and he held their relationship in high regard ... telling us Hayden "is the sweetest thing in the world."

Brian put it like this ... "It's not about who you spend Saturday night with, it's about who you spend all Sunday with, and Hayden Panettiere is a Sunday girl."

As we told you ... Hayden was found dead Sunday in a South Carolina apartment complex after flying down there with Brian. Her cause and manner of death have not been determined, but the dispatch audio from the 911 call mentions a possible overdose.

When we asked Brian in May if he thought Hayden was better off without him, he told us he would be an "idiot" not to walk away from her and let her "flourish in her career." He called her the most talented person he'd ever met, said they "probably wouldn't be good together," and said he was excited to see what she would accomplish in the next 30 years of her career.

Hayden was looking ahead to a better life too ... she went on a podcast around the time of our interview with Brian and said she had a lot of life to live and felt like she'd closed the book on a dark chapter.

Brian told us Hayden would always hold a special place in his heart.

You can catch Brian's full conversation with Charlie on YouTube.