I’m 39, and my ex-husband (38) has been dating a 24-year-old woman for three years. We were married for 12 years, divorced for five, and share three teenage kids. Our divorce was mutual, and we’ve always prioritized co-parenting.

Things changed a year ago when his girlfriend moved in. She always makes a wry face when I try to discuss something about the kids. She also told my daughters they “need to respect her authority now that she’s around and call her mom.” When they say they have a mom, she rolls her eyes.

Recently, she took my son’s phone to check his messages without asking and claimed it was to “make sure he wasn’t hiding anything.” My kids can’t stand her — honestly, I don’t blame them.

But the last straw came yesterday. She showed up at my house uninvited and DEMANDED:

“I want you to change your last name back to your maiden name. It’s ridiculous that we even have the same FIRST NAME. Oh, and you have one year — I want it done before we get married next January.”

I was shocked. This rude little brat needed to be finally put in her place. So I calmly replied, “Okay, I’ll do it. But on one condition.”

“You stop treating my children as if they’re part of your personal reality show. Respect their space, their privacy, and their choice to call you by your first name, not ‘mom’. You’ll act with the same respect towards them that you’re demanding from me.”

She looked taken aback, her face reddening as if no one had dared to challenge her like this before. But I wasn’t finished. “And another thing,” I continued, “if you ever take my son’s phone again, or try to enforce your ‘authority’ over my children, I will not only keep my last name, but I’ll also make sure they spend minimal time around you.”

For a moment, she seemed to falter, looking towards the car where my ex-husband sat oblivious, waiting. Gathering herself, she hissed, “You can’t dictate how we run our household.”

“This isn’t about running a household,” I replied firmly. “It’s about respecting children who are old enough to make their own judgments. They have a father, and they have a mother, and neither of us needs replacing.”

She stormed off, and later that evening, I got a call from my ex-husband. He apologized for her behavior and asked if we could find a way to smooth things over. I told him I was open to discussing anything as long as it was about the kids’ well-being and happiness.

The next few months saw a marked change. She kept her distance, slowly understanding her place in the kids’ lives wasn’t what she had first assumed it to be. As for me, I did change my last name, not out of spite, but to start a new chapter of my life, where I set the terms of my identity, not a 24-year-old with a sense of entitlement.