Help dealing with a loved ones mental illness?

My boyfriend was recently put on medications for manic depressive disorder and anxiety (but has actually been diagnossed, yet). I've known he has been depressed for a while, and have found it quite easy to be helpful and supportive, since I have major depressive disorder and can relate to him. But these past few days he has been so irritable, and every time he snaps or rolls his eyes my anxiety gets to me. I can't take a Xanax everytime I see him, we live together! How do I help him, and deal with him? And how do I not worry that this stress isn't what I cause everyone else, since they have to deal with me and my mental illness?