Objectively, you're right. However, if her motivation for using the condom is to protect her life, that is a mitigating factor.
The only correct answer to this problem is abstinence and cultural change. Any other "answer", such as the one you propose, will result in more death, and more suffering in both the short and long term.
How? What do you do for the women who are exposed while we're waiting for this "cultural change" to take place? Just tell 'em "tough luck"?
This whole issue is like the "cases of rape and incest" arguments for abortion.
Nope. Abortion involves intentionally taking the life of a fetus. Using a condom, in this situation, protects the life of a mother.
To think that protecting women exposed to AIDS will somehow result in the collapse of the Church's teaching on contraception leads me to wonder how strong you think that teaching is in the first place. I think it's strong enough to admit of an exception like this.