Don't know how much help I can be but I do sympathize about the family situation...mine is your worst nightmare and I disconnected from all of them years ago...for other reasons than religion but also religion because they of course attempted to justify their actions with the Bible thing...fuck em. I can only say what worked for me during my particular crisis. Keep one thing formost in your mind..."You are living in the Bible Belt" and EVERYONE with very few exceptions will try to "SAVE YOUR WRETCHED SOUL"...your Agnostic/Athiest AND you have a serious Medical condition. This leaves you wide open for a coordinated and/or disorganized but fervent all out assault. All I can say is ...might as well accept it if you already haven't that this is something "YOU CANT CHANGE"...BUT you can gracefully and elegantly and very intelligently RESIST...and still get the support you need. I had to do it when I had my crisis and it made me stronger about my Athiest stance than before because it allowed me to accept what was good in these people who really did care enough to help...and that's all I did was accept what was good and I returned their kindness in kind. Without ever swaying or bending to their Will. Believe me they tried. They tried every trick in the book including the "Guilt Card" and in my situation that was the worst thing they could do especially because I have prepared for it my entire adult life.
Most mean well...some are...well...just mean. You can pick and choose and if your lucky have a spirited(no pun intended but I'll happily take a freebee...hahaha) conversation and actually cement a friendship. If. Family is too much your going to pretty much have to rely on the local menagerie. It will be a shit show till you get the hang of it but sometimes we have to rely on what is available...your where you are...you can't change that obviously or you would...its like backpacking ... You learn to use your resources. You don't have to worry about being converted...just worry about what's important and realize that all religious people are not bad...just misguided(but don't accuse them of that...duhhh...lol)
I don't know how helpful this is but feel free to message me if you need a shoulder. I'm a good listener if nothing else. Namaste

Once I heard that half of the medicine/s we need is to live in peace and WITHOUT STRESS.
I know that to hear "Praise the Lord / Oh God...." and the likes 24 x 7 will stress me so much as to worsen up everything.

Seek for peace and beauty...

You will make it OK

I don't know.