The `X Factor` judge was devastated when intimate footage appeared online of her and former lover Justin Edwards and she claims he was the person responsible for it, something he denies.
But now a lawyer for Tulisa has issued legal papers against Justin - also known as MC Ultra - to prevent him talking about the video.
A source told The Sun on Sunday newspaper: "He feels he can`t talk publicly now because of this.
"She`s suing for up to 100,000. This latest move by Tulisa has really unnerved and unsettled him. It`s serious stuff and he`s got to take it seriously. It`s a lot of pressure for him.
"This is an unusual case, in that the injunction was granted after the material became public, not before. It entitles Tulisa to seek damages."
Tulisa - who got a High Court injunction last week to ban the video after it was leaked - wants damages for breach of confidence and privacy after the video of her performing a sex act went up for sale on the internet.
After the tape was leaked, Tulisa posted a YouTube video admitting she was "devastated" and blamed Justin.
She said: "As you can imagine, I`m devastated, heartbroken and I`ve been in bits for the past few days. When you share an intimate moment with someone that you love, that you care about and you trust, you never imagine for one minute that that the footage may at one point be shared with the rest of the UK or even people around the world, so as you can imagine, it`s a pretty tough time for me."
However, he hit back on twitter saying: "To find the truth both sides of the story should be heard b4 passing judgement #thatisall.
"I believe in silence being a sign of Integrity but in this case I guess I`ll have to speak up and Lay out the facts and let you guys decide. (sic)"