During the past season of "Teen Mom 2," viewers witnessed Leah Messer's ongoing custody struggles with her ex-husband Corey Simms -- and earlier this month, a West Virginia judge ruled that Ali and Aleeah's father would be awarded primary custody (caring for their girls Monday through Friday), while the mother of three would have her daughters on the weekends. Now, the 23-year-old is breaking her silence about the ongoing battle with her former husband and this co-parenting change.

"It was like a slap in the face," Leah tells Us Weekly in their latest issue, referencing the moment she learned the court's decision.

The publication explains that Corey initially scheduled a hearing back in August because the five-year-old girls were not arriving at kindergarten on time. While Leah admits they were tardy once, the MTV cast member insists the other accusations are simply not true -- and she even set up a school-board meeting to dispute the claims.

"I talked to the superintendent,” she explains to the magazine. "I’m sending them the [time-stamped] pictures I took to prove the girls were not tardy. They’re going to take them off.” The magazine added that school officials could not be reached for comment.

But that is only one component of her ongoing battle: Leah filed a motion to reconsider the custody change and hopes to eventually share 50/50 custody with Corey.

"I feel like they should have both of us in their lives,” she says of her twin girls. “At the end of the day, my kids are going to be happy, and I don’t care what I have to do to make them happy."

To read more from Leah, pick up a copy of Us Weekly, which is on newsstands now.