annie, the opening post in this thread addresses some of what you asked about.
Your description of the music shop experience sounds like you stumbled onto an idiot. My thought would be to to try find someone else to help you, at a different shop if need be.
I will answer your questions from my personal perspective. I'm a middle-aged male. Whether my experience would be materially different were I a woman, I can't say.
What instruments do you play?
Guitar. By "play," I mean I strum chords to accompany my singing. I decided to put my efforts into learning lots of chords (= more songs) rather than into learning picking (= better guitarist).
How long have you been playing?
I started about 22 years ago. As most folks will relate, the first few months can be quite trying. I was highly motivated (internal desire) and plugged along, but it was at least two months into regular practice before I could "do a song," by which I mean use three simple chords in a reasonably smooth fashion.
Do you play more for family, friends, or for yourself?
Basically for myself, though I certainly appreciate the ego strokes when anyone seems to enjoy what I can share--or compliments me on it! I started learning guitar after being on a camping trip where we were singing 'round the fire, and the guitarist didn't know how to do certain songs I requested. I realized that if I wanted to be SURE there was accompaniment for the songs I wanted to sing, I would have to provide it.
Do you feel supported in your musical choices?
My wife certainly accepts and supports what I do (bless her). I don't recall anyone else in my family ever asking me to get out the guitar. Friends' support levels run the gamut.
My "musical mission" is singing songs that don't get heard enough. Sometimes this translates into "songs that no one has heard of." There are some very popular songs by very popular artists that everyone seems to know, but that I don't really like (or got sick of after the 784th hearing). Occasionally someone listening seems to get stuck on the idea that I SHOULD know a certain song. I find that somewhat disconcerting when it's a song I don't even want to hear, much less learn to sing and play. Moral--not everyone will appreciate what you do, it might as well at least make YOU happy.
What is your advice to a middle-aged woman just starting out in music?
Be prepared for it to be a bit discouraging to learn the guitar (those fingers never had to do THAT before!). Make sure the guitar you use is "set up" reasonably well--if it's improperly adjusted for your needs it might be nearly unplayable. If at all possible, get a knowledgeable friend to help with guitar purchase. By that I mean, each guitar has to be judged by itself, you can't necessarily rely on make and model to assure there are no problems. With a decent (does not have to be expensive) instrument, it can be relatively pleasant to learn.
Seek out others you can play with and learn from. A musical community can be a great resource, as well as a joy in itself. Comrades with positive attitudes are a wonderful blessing.
Think about what YOU want to do. It doesn't hurt to have some exposure to musical genres or instrument techniques that aren't exactly up your alley, but satisfy your personal musical desires that brought you to this point.
Is there anything you can share, good or bad, about how music shaped who you are today?
That seems like a terribly profound question at this moment, so I'll give it some thought. It's hard for me to imagine anything bad in that area, though.