Not good.
Weed can cause paranoia/anxiety...not good for the anxiety you already have. It's also sedating, so mixing it w/ benzos I would think is not good. I don't know about the SSRI's. You really have to be careful with any other meds/drugs when taking benzos. They are one of the most dangerous to mix things with, even OTC meds, for colds, allergy's etc....
I'd google the RX sites to see the interactions of the SSRI's and benzo you have.
Take care ; )