Chronic lack of patience & rudeness

My husband is constantly speaking very rudely to me when he feels he is not getting my full attention at the exact second he wants it.  There is an incident nearly every day its worse when he forgets to take meds or  before he takes his meds  in the morning but happens when he has had his medication too.

If I am busy doing something and don’t drop my activity right away and rush over to where he is to pay attention to what he want me to he makes some rude statement or gets mad and says “forget it”.....even if only a 30 second delay to when I was going to talk to him.

He is frequently doing something else when I am talking to him, but if I do the same he tells me I am checked out and not paying attention and speaks rudely to me.

He spends a good  chunk of time everyday playing guitar, surfing net, doing his own thing  and most of the time I don’t bother him while he is doing these activities. If I do need  to talk to him he is very rude to me.  If I am doing something I want to do and don’t want to drop it to pay attention to him right at the second he wants me to, I get attitude or rude behavior.

 I feel that I have and continue to extended a lot of patience to tolerate his ADD related behaviors and I get zero tolerance back if I am not doing what he wants me to do when he wants me to do it. 

I am very tired of the constant one way street of tolerance  and being treated rudely  and also tired of the constant conflict if I stick up for myself for the way he speaks to me.  Suggestions?