4:26 PM PT -- OnlyJayus is firing back at her ex ... saying her request for a restraining order is filled with falsehoods and things being taken out of context.

The TikTok star tells TMZ ... "Unlike Brittany, I have been respecting her request for no contact for a couple of weeks now, including blocking her on all platforms, and I have not engaged in any behavior that would justify these allegations."

She adds ... "I take accusations of this nature very seriously and will be addressing this situation through the appropriate legal channels. I have no history of harassment or abusive behavior and am committed to maintaining my privacy and focusing on my well-being during this time."

TikTok star OnlyJayus is not taking a recent breakup well, at least according to her ex-girlfriend ... who claims she keeps showing up unannounced in the middle of the night.

Brittany Lee Dejardo is seeking court-ordered protection against Isabella Avila, AKA OnlyJayus, AKA Bella Rose, claiming her ex keeps coming around her home, is verbally abusive, and uses her massive social media accounts to berate her.

In new legal docs, obtained by TMZ, Brittany claims she told Isabella to leave her the hell alone ... but she says Isabella is not respecting her boundaries ... and it's getting toxic.

Brittany says Isabella keeps trying to contact her ... usually by showing up to her house unannounced. She says things reached a head Aug. 24 when OnlyJayus showed up at 2:45 AM.

In the docs, Brittany also claims Bella constantly verbally abuses her and uses social media to lash out and "continue the cycle of toxicity."

Bella has 18.1 million TikTok followers, and Brittany says she's scared of Bella's actions and words because "she can easily turn millions of people against me and she stalks my every move online and contacts people I follow."

Brittany says she's blocked Bella on social media and blocked her number, but she claims her ex is undaunted and keeps messaging her by any avenue possible ... on top of coming to her home.

Now, Brittany says she feels unsafe whenever the doorbell rings ... or when a red car pulls up out front ... and she claims Bella has access to a handgun.

What's more, Brittany claims Bella has a history of rage against other exes ... and she says when they got into a fight last Halloween and broke up, Bella threatened to hurt herself.

Brittany beelined it to court Tuesday and asked a judge for a temporary restraining order preventing Bella from contacting her or getting within 100 yards of her, her home, or her job.

We have reached out to a rep for Bella for comment ... so far, no word back.