I second Kevin's comments to some extent - people online tends to be weird and mean. Anyway, if you are opening up on the Internet is because you really need a hand. I'd first check with your health or wellbeing department (I'm not sure if your company has one, but as far as I know, major companies do) if they provide counselling or something like that. On the other hand, your manager needs to know this condition you have - if you productivity is low enough to make them consider kicking you out, maybe bringing your condition in that point wouldn't help and it just makes them think you are making that up to get away with it. If your boss is as cool as you said, then he will understand - being honest is a key. If someone in my team would have such problem, I'd like to know it. All of the above will help in the short term, but I strongly recommend you to get professional help - mental health is not to be taken lightly and even when someone (or even yourself!) could say you are just overreacting, they don't suffer what you suffer. Stay safe and remain calm please!

I'd first check with your health or well being department (I'm not sure if your company has one, but as far as I know, major companies do) if they provide counseling or something like that. 

On the other hand, your manager needs to know this condition you have - if you productivity is low enough to make them consider kicking you out, maybe bringing your condition in that point wouldn't help and it just makes them think you are making that up to get away with it. If your boss is as cool as you said, then he will understand - being honest is key. If someone in my team would have such problem, I'd like to know it. 

All of the above will help in the short term, but I strongly recommend you to get professional help - mental health is not to be taken lightly and even when someone (or even yourself!) could say you are just overreacting, they don't suffer what you suffer. Stay safe and remain calm please!