What began as a missing person's case has ended in tragedy. Kim Cattrall's brother has died at 55. 

When Kim's former costar, Sarah Jessica Parker, reached out with her condolences, Kim Cattrall shot her down. 

As you can hear below, no one is more flabbergasted at this than Andy Cohen, who has waded into this feud to defend Sarah Jessica Parker.

After Sex and the City actress Kim Cattrall's missing brother's body was discovered, she shared the crushing news on Instagram.

Among the flurry of sympathetic responses was a comment from Sarah Jessica Parker.

"Dearest Kim, my love and condolensces to you and yours and Godspeed to your beloved brother. xx"

Kim's reply was ... intense.

"I don’t need your love or support at this tragic time @sarahjessicaparker."

The message, a full post on Instagram, continued, and Kim Cattrall made herself every clear.

"Let me make this VERY clear. (If I haven’t already) You are not my family. You are not my friend."

That's ... extremely harsh.

"So I’m writing to tell you one last time to stop exploiting our tragedy in order to restore your ‘nice girl’ persona."

While Kim Cattrall is certainly grieving, the level of enmity here is palpable. And it's also nothing new.

This is where Andy Cohen comes in, speaking on his SiriusXM channel, Radio Andy.

"I thought it was fake. I was like, ‘There’s no way Kim Cattrall has posted this on her Instagram.’ This is a women who is in the middle of grieving the loss of her brother, which is tragic and sad."

It is a crushing loss. But Kim really did post that on Instagram.

"She accused SJP of exploiting a tragedy … She follows Kim on Instagram, Kim posted about her brother dying, and she expressed her condolences on the post … She posted it in a comment!"

Posting it in a comment, which is quickly buried under other comments and doesn't draw people to your own page, is generally seen as more respectful if you're walking on eggshells and don't want to be accused of exploiting a situation.

Andy Cohen goes on and continues to express his bewilderment.

"I would not call that ‘exploiting a tragedy.’ What was she supposed to do? Say something bad? I mean, I don’t understand."

Most people are lucky enough to not understand what Kim Cattrall is going through, but that doesn't necessarily excuse an entire post dedicated to blasting a former friend over condolences.

"I also don’t like it that people are characterizing this as a catfight."

The way that Andy sees things, it takes two to tango, this thing -- whatever it is -- seems to be very one-sided.

"There’s only one person fighting here … I even kind of, admittedly, didn’t try to stir it up on Watch What Happens Live when Sarah was on, but I was like, ‘What do you think?’ Sarah only said the nicest things about her … It’s a catfight of one from where I see it."

Admittedly, we're inclined to feel the same way as Andy does -- rudeness and hostility on this level is shocking.

At the same time, if someone's made it clear that they don't want you in any way to be part of your life, it's good to respect that, even if you find it hurtful or unfair.

Even so -- one wonders what sorts of things people would say about Sarah Jessica Parker if it became known that she had said nothing about Kim's loss. It's a no-win situation.

Listen to the rest of Andy's comments and decide for yourself if you agree with his characterizations.