According to new legal docs, obtained by TMZ, Jackilyn Martinez beelined it to court Friday ... claiming Blueface made false and defamatory statements about her and her child.

In case you missed it ... Blueface and Soulja Boy have been beefing heavily on social media this week, which started after the two began arguing about who would win in a Verzuz battle.

Well, things escalated quickly ... and Blueface made some pretty outlandish comments to Soulja Boy about Jackilyn, which includes, "Because I fucked your baby mama the day before your baby shower."

The docs say Blueface went on to say things like, "Till Soulja get a DNA test that's my child lil bro I'm the daddy now," and "What's old about your baby mama sucking my d--k."

However ... the docs say Jackilyn and Blueface did have protected sex one time in 2018, but since then there's been no sex of any kind.

Jackilyn's attorneys say they sent Blueface a cease and desist letter on Tuesday -- demanding he remove all these defamatory statements from social media -- but instead he mocked Jackilyn by posting on IG, "Nobody ever said your name ... I don't even know who you are."

Jackilyn claims she has been receiving death threats since it became known she sent Blueface a C&D letter.