Hi Rose,
I understand the guilt you feel. it's hard when you feel you're capable of working but know the stress that goes along with work can have such a negative effect.
I also agree with the others and think you should apply for the SSDI - I'm also wondering if you can apply for temporary disability while you are waiting - in my state you can file for something called "disability during unemployment". Maybe they have that where you live and you wouldn't feel as badly about being available and ready for work.
Like lavieenrose, I have that same fear of workplace stress - I'm currently looking at going from full time corporate to part time working from home, to alleviate the stress on the job. We have to do what's best for ourselves to stay healthy and happy.
You do not have poor character. This is not your fault. Many people apply for SSDI and i've never heard that it was humiliating - there is a reason for it and you have been paying into it in your paycheck all of these years - take advantage of it. It's ok to need help and ask for it. You are not alone.