I can identify with many aspects of your post. I've been slowly winning a war with the depression/anxiety monster for six years.
I too am the "together" one that friends come to for advice. They never even suspected. I could never talk to most of them about it, even now when I am so much better than I used to be.
Talking to your friends can be extremely disheartening. It takes a really special person (who has never experienced depression) to be able to listen without trying to fix, and to not run away from the scary thoughts you are no doubt thinking.
While friends and family may not understand, or want to understand, you are FAR from alone. Please go to your doctor ASAP. Get into group therapy. Talking about your feelings and every insecurity and horrible thought you have and realizing other people feel the same things is an immense relief. Get into individual therapy, because there will be more time to focus on the issues that are particularly troubling to you. I can definitely recommend interpersonal therapy, having suffered through my own mother issues. Cognitive Behavioural Therapy (CBT) was not as helpful for me personally, but I know people for whom it has been a great success. There are other types too, but I won't get into them here.
I know there is a wide range of opinions regarding antidepressants in the world, but without the drugs, I wouldn't still be here. That's a fact. I have worked very hard at half a dozen types of therapy and continue to do so. (Not currently working with all of them; some were right at different times in my depression and don't apply now.) Medication is not the answer for everyone, but if it helps YOU, then TAKE IT. Short term, long term, whatever. Don't let anyone else's judgement deter you from helping YOURSELF.
When you most need the help is when you are least able to ask for it. You have done an amazing thing, putting yourself out here, exposing yourself to us. I have every faith you will receive the support you need and deserve.
Again, go to your doctor. You do deserve the care that can be offered, and don't you dare feel guilty for asking for it.
Incoming PM from me with more personal contact information.