Effexor may help your depression but I don't think it will do anything for benzo withdrawal.
I was (sadly) on benzos for thirty five years and this included many long tapers.
The usual for tapering tabs are valium or rivotril as they have long half lives.
Benzo w/drawl can be very unpleasant and tapers reduce some of this.
Hang on in there;getting that stuff out of your system is well worth it in the long run.