If it's any consolation, I'm in my 40s and I have 3 kids and I honestly have days where my burnout and anxiety is as bad as you describe. I don't think it's not having kids that is your problem, I think you're probably predisposed to having an anxiety disorder and you're going through your mid-life crisis. Note that I'm not downplaying the seriousness of your situation by calling it a mid-life crisis - the mid-life c…
To some extent, my brother in-law's experience helped me get through mine because I was able to join the dots and identify my mental bullshit as coming from the same place as his, and try to avoid making the same mistakes.