I felt that way for years throughout my career and suffered crushing depression for it. Finally, my wife suggested that I retire, so I did. They honored me with a retirement party and my boss / business owner told me that he was very sad to see me go and that in all the years of the business; I was his best employee.I feel like lately i am being a burden on my coworkers. I have executive dysfunction, work too slow and have trouble understanding unsaid things.
I feel like i don't deserve my job basically and that i am deceiving my employer and everyone else by pretending i am NT.
I was floored and totally dumbfounded. All those years I felt I was on the razor edge of being fired. Like you, I am slow, I don't work well with others and there are a lot of required tasks I just couldn't do. Someone else always had to do it for me.
I learned that it is very hard to see yourself from others perspective and what your value really is to them. Since you have not been fired, perhaps your value is greater than you think. Perhaps your are actually worth more than the negatives of all your difficulties, slowness, etc.