A Pennsylvania bride made a touching promise to her husband's ex-girlfriend and her son

When a Pennsylvania bride read her vows to her groom on her wedding day, she made sure to include two other people in the ceremony—her new husband’s former girlfriend and the young son they have co-parented together.

Katie Musser began dating her future husband, Jeremy Musser, in 2013, and soon found out he had a newborn son, Landon, with his former girlfriend, Casey Bender. Things started off rocky between Katie and Bender, and the thought of one day becoming friends seemed far from a possibility due to the tension between them. But as time passed, the two ended up becoming friends. So before Katie read the vows she prepared for Jeremy during their September 23 wedding, she paused to make a few promises to her new stepson and his mother.

Credit: Bob Hogan Productions

“I was struggling for the longest time with my vows in general,” Katie, 24, tells PEOPLE of coming up with the idea to include Landon and Bender in her vows. “I felt as if I was missing something and I realized I was missing the things that formed our relationship.”

Credit: Courtesy Katie Musser

In an emotional video of the ceremony, Katie unexpectantly turns to Bender to read her the vows.

“First I want to thank you for accepting me as your friend and allowing me to be a part of Landon’s life,” Katie says to Bender and her husband, Tyler, in the video. “I promise to be an amazing mother to your son. I will guide, teach and love him every single day.”

Bender says she was surprised by the touching gesture.

“My reaction was complete and utter shock,” Bender, 25, tells PEOPLE. ” I was blindsided by the whole thing, but looking back, Katie is that type of person. She loves to love and she will show it to you by any means necessary.”

After reciting her vows, Katie bends down at the altar to Landon, 4, and reads him a series of promises made specifically for him.

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“I promise to stand by you, listen to you and love you every day,” Katie, of Lansdowne, Pennsylvania, says. “I promise to love Daddy with all my heart. I promise to be a best friend to your mommy and your daddy Tyler. We will be one big family that I promise you will have for the rest of your life.”

Credit: Courtesy Katie Musser

Even though seemingly everyone at the ceremony was wiping away tears, Katie says the only thing that helped her to hold back her own was how much she practiced before the big day.

“I was holding back tears, but I practiced so much because I was so nervous I wouldn’t get it out,” she says. “I wanted to make sure people heard what I said and the meaning behind it.”

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Learning to co-parent Landon has been a long road for both women, but they are thankful they were able to set aside their differences to become real friends.

“There have been lots of feelings towards the way Katie and I choose to settle our differences and do what was right,” Bender says. “We never in a million years thought we would be able to be this much in each other’s lives. She is my best friend and I am so thankful for her and the lessons she has taught me.”

Credit: Courtesy Katie Musser

Before the wedding, Katie gave Bender a bracelet as a token of their friendship.

“Casey and Landon… saved me,” Katie says. “They opened me up to so many situations. I could never show them how much it means to me.”

The two friends say the path toward peaceful co-parenting was a difficult one, and not every co-parent has to become as good of friends as they’ve become, but they should work together to put their best foot forward.

“I want people to understand that there is hurt and there is pain in split-parenting, but if you do what’s best for the child, you will be happier in the long run,” Bender says. “I wanted to leave a better legacy for my children then nasty name calling split-parents. There is so much hate in the world that even a little bit of kindness can go along way.”