Although I'm sympathetic to her case, (as I understand it) she wasn't in her own home when she fired the shot. She had already left, and fired the shot into the exterior wall of house prior to re-entering to grab her son. I think one can argue for all types of extenuating circumstances, but "stand your ground" doesn't seem like one of them.

Note that I'm not defending the use of "stand your ground" with respect to Zimmerman, nor am I defending the prosecutor.

After writing that, I read what this particular article has to say, and here is the relevant excerpt:

At some point during the altercation, Alexander went into the garage. She claims she could not flee because the garage door was not working and she did not have the keys to her car. Alexander grabbed her handgun from inside the glove compartment and went back into the house. She fired a single shot at Gray, who was standing in the living room with his sons, ages nine and 13. The shot missed.

This article appears to capture some of the prosecution's position:

Second, as the judge pointed out in the ruling that denied stand your ground immunity, presumably Alexander could have fled the home through the back door instead of returning to the house and confronting Gray.

"Obviously, the jury believed the state's position, that she went into garage to get the gun and make a stand, and that's not going to be tolerated," Stone says.

…

And there are disputes about significant facts in the case, including whether Alexander could have escaped out the garage instead of getting her gun and returning to the house; Gray said he "knew she couldn't leave out the garage door because the garage door was locked" in his November 2010 deposition, but in her ruling against allowing Alexander "stand your ground" immunity, Judge Elizabeth Senterfitt wrote that "there was no evidence presented to support her claim."

So, I think I understand both sides of the story, but I still think other mitigating factors could have been brought into play. Of course, IANAL.