"I would love to give something back to you but I am not sure what that should be."

I would worry about creating an obligation that would require you to have anxiety and other issues by not being able to fulfill the obligation. While it's nice and might make you feel good to give back it's hard to believe that it wouldn't be better to simply try to get yourself stronger without the obligation of doing for others. For now.

After all even the simple act of "replying to all that wrote" appears to be more than you can handle right now. I'm sure some of those people would want to be acknowledged for taking the time to write.