INSIDE EDITION Speaks Exclusively to Levi Johnston's Mother and Sister

INSIDE EDITION speaks exclusively to Levi Johnston's mother Sherry and sister Mercede, who open up about the news of his engagement to Bristol Palin.

Levi Johnston's sister and mother are speaking exclusively to INSIDE EDITION about their reaction to the engagement, and they're not hiding their disapproval.

"I never thought this would happen. I don't think it's sincere. I think that there's something going on," says Levi's sister, Mercede Johnston. "Since he and Bristol got together, I haven't heard a word from him. When he told me that they were thinking about getting back together, I just started crying."

Mercede says that her big brother used to be her best friend. She gets teary when she thinks about the state of their relationship today. She has a blog that regularly bashes the Palins and says that an angry Levi recently called with a threat.

"Levi said I either take down my blog by Wednesday or him and Tripp will never be in my life, they want no part of me, and they won't talk to me, and I will never see them again."

INSIDE EDITION spoke to the Johnstons in Wasilla, Alaska at a hotel right next to the Palin family compound. They say that, like Sarah Palin, they learned of the engagement when Us Weekly magazine hit the newsstands.

"You would think that a normal family would call you and say 'Hey, I just got engaged!' And usually they would congratulate you and it would be a happy family celebration—but no. We found out through the media, which is a little heartbreaking and I think it's kind of rude," Mercede tells INSIDE EDITION.

So why do they think the couple got back together, even after a nasty custody dispute and a war of words between Levi and Sarah?

"I think there's something more to it than just love. Whether it's shutting Levi up because he has information on the Palins," says Mercede.

Levi's mom says she has more faith in the relationship: "I knew all along that Levi had loved Bristol."
So does Levi's sister believe his claim that he and Bristol are practicing abstinence before marriage?

Mercede laughed and said no.
Bristol has said she's "praying" that her mom will attend her wedding. Mercede and Sherry, who's on probation after a drug conviction, aren't even sure they'll be invited.

"I would be absolutely devastated if I was not invited to the wedding, that would be the last straw," Sherry says.