You are not the only one who is experiencing this type of feeling. I noticed that I tend to get irritated at the least little things, and that I also snap on people who mention things about MS. These feelings are normal IAW my neurologist, and psychologist. I did a little footwork a few days after being DX, and I found out that many patients have committed suicide.
Staying positive is much harder then people think. It seems like no matter how hard I try to forget that fact that I have MS, someone, or something reminds me..... very, very, frustrating.
A few things that help me control my temper are:
1) place myself in others shoes, and try to view my as they do so that I can understand them
2) Think of how much of a headache that I will get by stressing myself out
3) I usually walk away, or turn music on.
Good luck to you. ; )