It's very common for people to justify and downplay murder committed by women (as you do above). Your comment about women killing abusive husbands, while quite PC, is not supported by literally hundreds of studies that find equal rates of partner violence among men and women (violence of all types, not specifically homicide). Studies looking at motive typically find that men are slightly more likely to act in self defense against their female partners than are women to act in self defense against their male partners. You can find some studies at
DVStats.com Search Engine - tracks research on domestic violence against males. Unfortunately, in practice, the self defense argument is only available to women. A woman can successfully use this argument without evidence or substantiation. In fact, abuse doesn't even need to occur. Mary Winkler received a 2 month sentence for shooting her husband in the back because she claimed, without evidence, that her husband wanted her to dress up in high heals and perform unnatural sex acts. This is not a sellable argument for a man. Women can make excuses. Men cannot. This is one reason for the 10 to 1 disparity.
The Bureau of Justice Statistics performed a study in 1998 where they looked at sentencing disparities between men and women who had killed their partners of opposite sex. The study specifically eliminated cases where self defense was used as a motive. The study found that men who killed their female partners received an average sentence of 17 years. Women who killed their male partners received an average sentence of 7 years. The DOJ reported that they had no explanation for this disparity.
The bottom line is the following. There is a 10 to 1 disparity in death sentences given to men vs women. There is no disparity in death sentences given to whites vs blacks (if anything, whites are more likely to receive the death sentence). Why are people so willing to believe a nonexistent racial disparity but are completely unwilling to believe the enormous gender disparity? It's a rhetorical question, I know the answer. If the racial disparity was 10 to 1 (against blacks), I doubt too many people would argue that "we can't draw conclusions from the data," and then hypothesize that the disparity exists because murders committed by blacks are somehow worse than those committed by whites.