Help me Help my hubby!

Does anyone have any ideas of how to help a male who is manic depressive, calm down and enjoy LIFE more. My hubby can not seem to enjoy the good things in life and he is bringin me down too. I am a very optimistic person and no matter how much i try to help he just gets more mad and more mad at me. We figt almost everynight now and i dont know what to do?????
I hate fighting! We have been together for so long and we have been through worse times than this and he just seems to get worse with every year we are together???? Any ideas would be apprietiated?????