For the last three season, Mona has been secretly making The PLL's lives a living hell, but now that the doors on her black hoodie-filled closet have been thrown open for all to see, Mona's not trying to hide her hatred any longer.
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Something we got a taste of last week when Mona tossed Toby in Spencer's face, and the two are going toe-to-toe once more in this Tuesday's all-new Pretty Little Liars!
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Titled What Becomes of the Broken-Hearted, the hour sees Spencer continue her long descent into self-destruction and takes her anger out on Mona. But Miss Vanderwaal won't sit back in silence while she's verbally assaulted as you can see in ETonline's sneak peek clip!
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And for those of you who think Mona's no match for Spencer in the long run, remember what PLL EP Oliver Goldstick told me: "What's great about Mona is that she's kind of like the bizarro Spencer in some ways. There is no off switch to their brains, and Spencer has a match in Mona so they go toe-to-toe in 3B. It's a lot of fun."
Watch the fun play out above and on Tuesday at 8 p.m. on ABC Family.