Fran, 23, has strongly denied Grace's claims after viewers watched the pair's simmering feud come to a head in last night's episode (16 July).
Recently, viewers have seen Grace fall out with close friends Georgia Kousoulou and Fran, after it was revealed that she was still in contact with her ex-boyfriend, despite going out on a few dates with Tom Pearce.
When Grace came face-to-face with Fran and Georgia, the trio fell out, with Grace questioning their loyalty as she felt they weren't being supportive of her.
In last night's episode, while in Essex nightclub Faces, Grace told Fran of her distrust as a friend, saying she had "b****ed" behind her back.
Grace also dropped a bombshell to Fran, claiming: "I also think that you are a bit of a hypocrite. When you first got with Diags, you was still sleeping with someone else. And you done that for fun. I was in love with my ex-boyfriend."
Grace continued: "I'm not saying you was with him [Diags], but when you first started talking to Diags, you was sleeping with someone else."
In shock, Fran replied: "How dare you. I would never do that to my James. I would never."
Speaking exclusively to the official TOWIE website after the show, Fran said: "She's f***ing crazy. I wasn't sleeping with anyone else, I would never do that to my boyfriend. I love him, I've got too much respect to do that to someone.
"She's brought up someone who I was sleeping with and saying, 'but you wasn't with Diags', so why bring that up? What the f*** are you talking about?! It baffled me. Her comments confuse me."
Speaking about the state of her friendship with Grace, an outraged Fran continued: "I literally am so over her bull****. She's just trying to find some sort of issue with me and I really don't get it. I've got my friends and my family, I don't need her in my life.
"I genuinely have no idea because everytime she cried I was there straight away, but she feels that I wasn't for some peculiar reason, and that's cool. I put my hands out to her, I've been there for her, everyone else sees that I was there for her but she chooses to believe different. What more can I do?"
TOWIE airs Sunday and Wednesday nights at 10pm on ITV2.
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