"If you always do what you've always done, you'll always get what you've always got." Get out & experience life.

"Mental Health Support " - maybe joining other folks with issues - who can offer suggestions - and who may have been down the road you are on - will help you. Just click the link.

You could spend a bit of time & money to transform the double-wide, which a homeless person would consider a princely castle.
You could start taking walks with your sister, and maybe make some healthy food for both of you.
You could bring the 70-year old on the walks, or drop him on a bench along the way.
What I am trying to tell you is, whining does nothing to improve things, and taking even tiny actions will give you a satisfying feeling of being in control instead of enjoying being a "victim"

First of all, 37 is the right age for a midlife crisis. Get it out of the way early.

And you really do live a miserable life! You actually make me feel better about my life. My life is just empty. I don't have leeches hanging onto me, I live in a real house that's paid for, and I will never be bothered by relatives. I suppose my corpse will be found by someone who turns off the utilities due to non-payment.

Have you ever tried telling a doctor about the social anxiety? And seeking treatment or counselling? Or going to a support group for people with social anxiety? If it is such a hindrance to your quality of life I highly suggest you seek medical care for it eventually.

I guess the question is, do you want to change this? How bad? Would you consider therapy? There are groups to help build self confidence and deal with social anxieties. There are also plenty of books with plenty of tips to get you started. The important thing is to be brave, take those first steps and do what you need for your sanity.

If I were you in your situation feeling the way you do, I'd start with assessing it; writing it out, exactly as you have done. I'd continue that. Now it looks like you care about yourself and your family and that can be work. Think like a janitor and use this as an opportunity to work on your own capacities and create order in your life and those surrounding you. Fostering a sense of gratitude for your work, even though you might rather be doing anything else is also the work. With compassion.

You’re in a rut and only you can get yourself out of it. You are now 37, what is stopping you from living a life independent of your family?