Brittany Furlan Files Restraining Order Against Ronnie Radke

3:21 PM PT -- The TRO was denied by the court clerk because it's not an emergency order ... the judge will rule January 23 on the issue at the hearing.

Brittany Furlan says Ronnie Radke just won't leave her alone -- blasting him as "unhinged and obsessed" -- and is seeking court-ordered protection from him ... while denying she ever got catfished.

Brittany just beelined it to court and filed for a temporary restraining order against the Falling In Reverse frontman ... saying he's been harassing her online ever since last year's "secret relationship" that crumbled.

In new legal docs, obtained by TMZ, Brittany says she was definitely communicating with Ronnie on Snapchat last year during a difficult time in her marriage to Tommy Lee, and they sent each other explicit pictures and videos and made plans to meet up.

Ronnie's claimed Brittany was chatting with a catfish ... but she says all of the comms were legit and could not have been A.I.-generated "due to the explicit nature of the content."

Brittany says Ronnie begged her to leave Tommy for him and they made plans to meet up in May ... she says Ronnie told her to go to his former address and she claims she showed up and got stood up ... and that's when he allegedly started intentionally humiliating and manipulating her.

BF says she told Tommy what happened and he confronted Ronnie online ... but she says Ronnie then started spreading a false narrative that she was getting catfished.

Brittany says Ronnie then began annoying, harassing, and mocking her on social media ... and tried to humiliate her in a music video with "a hideous body double."

She says she wanted nothing more than to be left alone, but says Ronnie started leaving "cruel" comments on her IG from a burner account. She says she told the person behind the account she knew it was Ronnie, and the person responded, "Miss you madly," and included a photo of her from their old Snapchat convo, which she says reinforced her conviction that it was Ronnie all along and not a catfish.

Brittany says she tried to ignore all of Ronnie's mocking content until last week, when someone made a video about how she was allegedly catfished. She says Ronnie posted three videos on IG berating her, calling her a liar, and "intending for his fans to attack me."

As we first reported ... Ronnie filed for a temporary restraining order against Brittany last Monday, but it got denied ... and in her TRO request, she says Ronnie's TRO request was "frivolous." Ronnie also filed a lawsuit last week against his alleged online impersonators.

Brittany says Ronnie harassed and berated her and Tommy on a livestream and called Tommy a loser on IG ... and she says she reported the harassment to Instagram and got Ronnie's account disabled.

She says Ronnie "is unhinged and obsessed with me" and is simply asking to be left alone by Ronnie so she "may live in peace."

Brittany wants the court to order Ronnie to stay at least 100 yards away from her, her home, and her car ... a judge has yet to rule.