Emily Simpson has come a long way on her weight loss journey.

However, The Real Housewives of Orange County star isn't feeling so confident about her body after modeling in costar Heather Dubrow's charity fashion show for LGBTQIA+ rights.

In E! News' exclusive sneak peek at the Bravo series' Sept. 19 episode, Emily confronts Heather, saying she felt as if she was treated differently from the other castmembers during their runway debut.

"Can I ask you a question?" Emily begins in the preview during a group get-together. "So, when you asked for our measurements, when you texted us and told us all the things to bring, you asked me to bring jeans. So, when I got there, I thought everybody else was bringing jeans too."

While Heather insists, "No, everybody had different things," Emily points out she didn't get to model any pieces from Heather's new collaboration with designer Susan Bender.

"What bothered me and what was hurtful to me was that when I realized when we all walked out at the end, that I was the only one who didn't have anything on by Susan Bender," she continues. "Like, I had to bring my own pants."

Heather adds that she didn't know which exact pieces of clothing each of her costars were assigned before Emily breaks down in tears.

"I actually had a little moment where I went into the bathroom and I actually cried a little bit because I felt like I was singled out," Emily recounts. "I felt like I was the girl that couldn't fit into the pants that everybody else had on. It really killed me."

And when Emily adds that she felt like she "wasn't as small as everyone else," Heather offers a heartfelt apology, replying, "I'm so sorry."

In a confessional, Heather explains she never wanted her costar to feel like she was treated differently.

"I think Emily has a great body," the Let's Talk With Heather Dubrow podcast host shares. "I don't understand why all these insecurities are coming out now towards me."

In an attempt to comfort her crying costar, Heather tells Emily, "I would never do that. I wanted to make sure you had three changes, I wanted you in more things."

Emily clarifies she doesn't think her BFF did it intentionally by responding with, "I know that you wouldn't do anything malicious and I never think that about you. But I've worked so hard for the last 15 months to lose weight."

Heather's reply? "I thought I was giving you a starring role," she says. "I am so sad that you feel that way."

See how the drama plays out when The Real Housewives of Orange County airs Thursday at 9 p.m. on Bravo. 

(E! and Bravo are both part of the NBCUniversal family)