Serc,
Not to sound cliche, but there's no price that you can put on your happiness--this is something you understand and which you can weave into your application story.
In responding to your specific questions:
1) Although you're certainly on the older end for starting your MBA, it is certainly possible. Most classes will have individuals (though the number varies) who are in their mid- to late-30s. (Some classes even host a few applicants in their 40s.) What it generally boils down to is the story you tell and how you demonstrate that you "need" an MBA--specifically, this MBA from this particular program. So, if you feel that you need an MBA, then certainly apply. And, as others will likely point out, you do have the option to explore an Executive MBA too, if that is of interest to you.
2) Your age and experience may make it more difficult for you to earn some scholarships, but it is possible. Think less of the scholarship opportunities and more about the investment for your future--given that you have a particular post-MBA career interest in mind and you seem passionate about pursuing your next career step, would not receiving a scholarship actually stop you?
3) You should certainly explore which M7 schools you may be interested in. While your undergraduate GPA is not especially strong (though it is in a difficult field), your GMAT and resume can make you competitive and I imagine you may have access to some high quality recommendations. What it's going to come down to is how you communicate your story, especially through your essays and your interviews. You must communicate to an admissions committee how an MBA is the most logical next step for you, especially given your age. It's a challenge, but if you're interested in the M7 opportunities and you think you can make compelling arguments for the particular schools you apply to, then it is certainly worth the effort.
Best of luck as you continue down this path. And if you'd like a free 30-min initial consultation from one of our admissions consultants to give you some additional perspective or recommendations as you make your decision, we'd be happy to help.
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