You need to talk with several folks....
1st Sgt.
Commander
Chaplain
and, most importantly, the Mental Health Clinic.
If you wife is suicidal, she needs to be seen and seen quick!!
While your service to your country is needed, you cannot be the best soldier, or any kind of soldier, if your wife is at home, grieving over the loss and feeling suicidal.
Once you talk with these folks, they will help you work out what is best for you and your family. Since it is still a few months out, they may get you and especially your wife in counseling now and work toward helping her deal with this, and hopefully overcome her feelings of suicide.
As a mom of 4, but only 2 living children, I know what your wife is going through. And your imminent deployment is probably not helping. She really needs to talk to a professional and get help. In the meantime, hold her, comfort her, and let her know that regardless... you still love her and that life has to go on! If hubby and I had given up after our second, we would not have the two wonderful girls that we have now. I still grieve for the others on occasion, but the hurt does lessen with time.
Hugs to both of you!!