Stephanie Pratt Says Heidi and Spencer Are 'Full of S---' In Awkward, Heated 'Hills' Aftershow Confrontation

This family feud is just getting started.

Spencer Pratt's ongoing battle with sister Stephanie will clearly be a season long storyline on "The Hills: New Beginnings" -- and, based on this aftershow interview, they still haven't patched things up.

Following Monday's premiere, the entire cast was interviewed by Michael Strahan and Sara Haines on MTV, with Spencer and wife Heidi Montag appearing via satellite.

As Speidi listened, Stephanie laid out her issues with her bother, after touching on the drama during the premiere.

Explaining that she lived in London and "didn't really have a relationship" with Spencer or his wife, she expressed her shock in learning they were having a baby via The DailyMail ... on her own birthday, no less.

"I was obviously really hurt by my mom and by them not telling me," said Stephanie. "I think in a family, you would know these things. And I do think it's odd the baby was not born on my birthday, but they announced it on my birthday."

Heidi, however, explained why they didn't clue her in ahead of time.

"It's a hard situation for everyone, because we have only seen Stephanie a few times. It's been challenging, because when we see her everything's fine, and when we leave all these mean articles come out about us," she said.

"So we couldn't trust her at that time, unfortunately, to tell her we were pregnant, because we did have a deal with a magazine and we weren't on great terms and we didn't know what she would say," Heidi continued.

She claimed that they did tell Stephanie the day the story was to come out, but "maybe with the time change" they didn't let her know in time. Stephanie then doubled down on her claim nobody ever told her.

Spencer was sarcastic as ever when he was asked about his sister, saying with a smile, "I'm so thankful Stephanie moved back from London, she is such a treat and it's so awesome." Stephanie, however, wasn't having it. "They're both full of shit and you'll see it all series long," she hit back.

Later in the show, Heidi said she was "always for patching things up" when it came to Brody Jenner's relationship with Spencer. This, once again, set off Stephanie.

"Can I just cut in really quick? I love that you just said that, Heidi," she interrupted. "If you really did love patching up relationships, for all the years I didn't speak to Spencer, I don't know why you never said, 'Come on, you guys are family, get together.'"

"If I was married to someone and they weren't getting along with their mother or family, the first thing I would do is be like, 'This is silly, you guys are family,'" she continued. "Did you ever reach out to me? No. You probably promoted it."

Montag tried shutting down the tangent, telling Stephanie, "I think we've moved on from that part right now." And move on from there they did.

"The Hills: New Beginnings" airs Mondays on MTV.