The ladies got into a heated argument when Morgan sided with Heather Thomson -- who rather harshly excluded Singer from a girl's trip to London. But looking back on the fight, Singer tells Us she's not angry with Morgan.
"Good friends are allowed to speak and say what they feel when they're feeling rotten, that's my opinion. I think Sonja backed me up on that," Singer, 55, explained. "I think she was shocked by what I was saying because she really had no idea. At that point, she had no idea that Heather had invited everyone [LuAnn de Lesseps, Carole Radziwill, Aviva Drescher and Morgan] but me. So she really didn't know any of the situation."
So fans of the twosome (who, along with de Lesseps, are the only surviving cast members from season 4) can breathe easy -- they've made up!
"Sonja's always going to be my great friend," Singer tells Us. "Sonja and I can fight like dogs and make up the next day like pussycats, you know? That's just the way we are."
And Singer added that she and Morgan, 48, have a lot in common: including their very smart daughters Avery and Quincy. "I think her daughter is a younger version of Avery," she says of Quincy, who doesn't appear on the series. "Avery's a straight-A student, her daughter's a straight-A student. Her daughter is extremely well-mannered and articulate, very courteous, very grounded," the Bravo star shared. "To me she reminds me of what Avery was at that age. She's like 10 and my daughter's 17, very similar."