If you are able to do so, bring her to an intro self-defense lesson for her to experience for herself.
It may change her mind. You may want to also show to her that there are so many styles of martial arts. If she is insistent on it not being "ladylike", it may be that her perception may be of the hard styles and MMA and not soft styles.
You are 35, no need to get mom's OK...go for it!