Brooke Smith with Sara Ramirez, Grey's Anatomy

It is the worst and last news that "Callica" fans expected to hear. But the fact is that Brooke Smith, who first appeared as Grey's Anatomy's Dr. Erica Hahn in May 2006, has been abruptly let go from the show - just as her lesbian storyline with Sara Ramirez's Callie was taking off. Ironically, series creator Shonda Rhimes broke the news to Smith in mid-September, just after the actress had filmed Erica's pivotal "I see leaves!" coming-out monologue. Her last episode airs this Thursday.

"I was very excited when they told me that Erica and Callie were going to have this relationship. And I really hoped we were going to show what happens when two women fall in love and that they were going to treat it like any heterosexual couple on TV," Smith tells EW's Ausiello, who first reported on her release. "So I was surprised and disappointed when they just suddenly told me that they couldn't write for my character anymore.

"I was really, really shocked," she stresses. "It was the last thing I expected."

In a statement, Rhimes says, "Brooke Smith was obviously not fired for playing a lesbian. Clearly it's not an issue as we have a lesbian character on the show — Calliope Torres. Sara Ramirez is an incredible comedic and dramatic actress and we wanted to be able to play up her magic. Unfortunately, we did not find that the magic and chemistry with Brooke's character would sustain in the long run. The impact of the Callie/Erica relationship will be felt and played out in a story for Callie."

The Grey's boss goes on to say, "I believe it belittles the relationship to simply replace Erica with 'another lesbian.' If you'll remember, Cristina mourned the loss of Burke for a full season."

Though ABC declines to comment on the reason for the unexpected ouster, Smith says that in her talk with Rhimes, she got the feeling it was dictated by the network. "I don't know for sure, but it definitely seemed like [Shonda's] hands were tied," she says, "like some decision came down from above."

Might have this frank exploration of two women coming to terms with new sexual orientations proven too hot for ABC to handle? Smith saw no such signs. "At work I had no sense of it. And more fans seemed to like it than not," she tells EW. "I don't think I'm ever going to know [why this happened]."

The answer may be obvious, if one looks at a pattern of recent story "twists" across ABC. Ugly Betty last season introduced with much fanfare Rebecca Romijn as a post-op transgender; now she's gone. Right out of the gate, Dirty Sexy Money lathered things up by pairing aspiring politician Patrick with a great transgender love; last week, she walked out of his life. So Grey's writing out a full-fledged lesbian such as Erica — versus the simply lez-curious Callie — would seem to fit this pattern. Meanwhile, gay males such as Brothers & Sisters' Kevin appear to go unpestered... at least for now.