Leah Messer ‘Angry’ Over New Custody Agreement, Ex Corey Simms NOT Invited To Their Twins’ Birthday Party!

Though peace has prevailed after their nasty custody war, Leah Messer is still on shaky terms with her ex-husband Corey Simms.

RadarOnline.com can reveal that the Teen Mom 2 star, 22, is livid that Simms, 25, and his wife Miranda will now have 4-year-old twins Ali and Aleeah for one extra night a week.

As RadarOnline.com exclusively reported, the former couple, who split in April 2011 after just five months of marriage, will now abide by a shared parenting plan allowing Simms to have the girls three nights a week, and Messer to have custody four nights a week.

Though Simms originally filed for primary custody, Messer still isn’t satisfied with the new arrangement.

“Leah is upset with Corey and Miranda,” a source tells RadarOnline.com. “She didn’t want to lose any time with the girls.”

In order to avoid her ex and his new wife, Messer is even planning to hold a separate birthday party for the twins when they turn 5 on December 16.

“There will be two different parties,” the source reveals.

Not only will her ex be absent from the bash. Messer’s current husband, Jeremy Calvert, 25, will likely skip the celebration as their marriage continues to crumble.

Robbie Kidd, 22, revealed yesterday that he did in fact have sex with Messer in early October, squashing her early denials of infidelity.

And as RadarOnline.com previously reported, Calvert has his own new love. The father of Messer’s 22-month-old daughter Adalynn sent sexy texts to hot single mom Brittany Musick, 27, just before Thanksgiving, claiming he was ready to move on from his two-year marriage.