I don't know the answer to the question I am posing but it's something I think you should research. It concerns age bias. While it may be illegal its often practiced by selection committees at least in the area of science that I do. The issue would be why invest the resources in training a 40 something who has 20 years less of a working life ahead of her than and 20 something? When I say resources, realize that student tuition is a drop in the bucket compared to the real costs to educate a professional of the type you are discussing.

I also wonder if an admissions committee would worry that this is your third career change, so it will be important to articulate why this time you are sure. Its easy to say you made a mistake the first time around, but the second time too?

I am not writing any of this to discourage you, just offering the perspective of someone that sits on admission committees for things to research before you take the plunge.