They’ve been enemies for a long time and things have only gotten worse between them. Now, the final straw has been reached, and it will lead to an all-out brawl between Mariah and Hilary on the Monday, May 8 episode of “The Young and the Restless.”

Hilary (Mishael Morgan) and Mariah (Camryn Grimes) have never gotten along with one another, and their time working side by side on GC Buzz has proven to be a major struggle. They have both made moves to sabotage one another’s careers before, and, their battles even helped propel Devon’s (Bryton James) decision to divorce Hilary. Now that Mariah is dating him on the CBS soap, Hilary is even more enraged and wants to hurt Mariah even more.

In Hilary’s mind, the best way to potentially get even with Mariah is to steal Devon back, and after realizing the two were on a romantic date on Devon’s helicopter, she broke into his apartment. However, her potential plans came to a screeching halt when Devon came back with Mariah, and much to a hidden Hilary’s disgust and surprise, the two began making love. Now, her jealousy is at a fever pitch, and when Mariah comes back to the office the next morning and once again gloats to her about the romance, it will set things off for the pair’s showdown.

“My life was sad and pathetic before Devon showed me the world and blew my mind,” Mariah says in a preview clip.

Hilary will be left fuming because she knows what Mariah is referring to since she became an unwilling witness to the two having sex, and her fury will continue to burn extensively as she also learns that Mariah’s relationship is also giving her even more perks—like access to the designer clothing that Hilary left behind at Devon’s when she moved out, among other luxuries Devon can provide her with. As her anger continues to grow, she may decide to once again snipe about Mariah on air, once again alluding to the audience that she is being delusional to just how far things can go for her. That move could be the one that takes everything completely over the top, and the two women may finally attack one another physically in a no-holds barred catfight.

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Meanwhile, Devon and his father, Neil (Kristoffer St. John), are still waiting to hear if Dina Abbott Mergeron (Marla Adams) will accept their bid on her company. Though the two feel it is the right move for them to make when it comes to their own business having a successful future, Neil will realize he needs to warn Jack (Peter Bergmann) and Ashley (Eileen Davidson) that he is going into business with the mother who deserted them both so many years ago.

“We are pursuing an international conglomerate,” Neil says to Ashley. “Mergeron Enterprises.”

That news likely won’t go over well, and if Dina does accept their offer and potentially comes to Genoa City to settle things, it may only make things worse for everyone.

“The Young and the Restless” airs weekdays at 12:30 p.m. EDT on CBS.