Alcohol and antidepressents don't mix. You add both and it will likely intensify the effects as well as cancel out the effects of the Zoloft.
I'm going to be flat out brutally honest... I'm sure you already know this, but drinking to cope with the loss of your brother is probably not the best coping strategy. Likely it's just making it worse for you and making the amount of time to grieve longer and harder to deal with in the long run.
You could try lurking the alcoholism forum. I'm not saying you are one. I'm just throwing it out as a suggestion, because many people there drank to cope with life problems that were better coped without drinking.
http://www.medhelp.org/forums/show/158
There are many kind and supportive people there. Feel free to check it out.