Spencer Pratt and Heidi Montag

Hills stars Heidi Montag and Spencer Pratt may be enjoying new marital bliss, but their elopement last week has been nothing but heartache for Montag's mom.

"[Spencer]'s manipulative and seems to have power over Heidi," Darlene Egelhoff, 46, told Us. Heidi skipped Thanksgiving with her family to head for Mexico with Pratt to marry him in secret. 

Egelhoff also revealed her suspicion that Heidi eloped under duress. "I would like to see a blood test from Mexico," she said. "It wouldn't surprise me if [Spencer] had her drugged."

Adding to Egelhoff's heartache, however, is her sense of growing distance from her daughter, which she attributes to Pratt's presence. "Spencer has tried to cut everyone out of her life," she lamented. "I've been honest with Heidi, and it's caused our relationship to decline. I'm more devastated about that than the marriage, because I'm confident the marriage won't work out."

Marrying Spencer, Egelhoff continued, was "the biggest mistake Heidi's ever made," adding that she gives the pair six months before their marriage falls apart.

Before you break out the Kleenex, though, let's get back to Speidi's roots in reality TV, where the newlyweds are firing back: "She should be happy I found someone I love," Heidi said, responding to her mother's criticism. "Some people go their entire lives without finding that."

Pratt added, "I think her mom needs to take a real fat chill pill and be happy for her daughter."

Egelhoff — who's previously fought with Pratt on The Hills — still carries a heavy heart. "God says love your enemies," she said. "But I never expected it to be my son-in-law."

Do you think Spencer manipulated Heidi all the way to the altar? Or is Egelhoff using a mother's malaise to self-promote?