Champix

I used Champix about 8 years ago to quit and managed to stay off cigarettes for 1.5 years but then had bad news and started smoking again but during the time I was not smoking and only took the Champix for two months, I was very depressed and had a melt down which lasted for about six months or longer. My doctor put it down to a delayed reaction to loosing my husband and has now prescribed Champix again but i am concerned if it really was a delayed reaction to my loss or was the Champix still in my system? Part of me wants to try it again but there is part of me that is frightened that I will have another breakdown?

Thanks all