Effexor + Arimidex = ?

Hi friends - I just started my arimidex (ER/PR+, HER2-, single mastectomy, oophrectomy) and I am completely depressed and broken, but petrified of anti depressants.  I keep telling myself that depression is just a function of the trauma of having breast cancer and being dropped off the menupause cliff with the ovary removal (not to mention that my father passed away right before my mastectomy), but I cry constantly and feel like I can't be a good mom.  I can't concentrate and get short of breathe often.  I have a history of eating disorders and my biggest fear is being put on medication that would cause weight gain because it would result in even greater spiraling depression.   Does anyone have insight on weight gain with antidepressants when put on top of Arimidex?  I also wonder in general if the side effects from Arimidex have REALLY 'kicked in.'  Im about 3 weeks into Arimidex.  Thoughts?  And thanks for the feedback.  So happy to find a network of people who 'get it.'

Leslie