I'm sure sorry to read this! Don't lose hope!! Xanax is not a great choice for long term anxiety treatment. It's also addictive which is I'm sure a concern you have now that you have taken them for so many years. And they aren't helping you with the anxiety anymore. Talk to your doctor about this even though that is a hard conversation. You say that ssri's are not options . . . but there are snri's and other classes of medications that help with anxiety other than the benzos. You have other choices. But if your current treatment is not working or not working very well anymore, please talk to your psychiatrist about where to go next. You need a different plan especially if you are becoming depressed! good luck
Have you tried to switch to regular release xanax or maybe a different benzo at this point like ativan? SSRIs are quite awful and also cause dependency just like the benzos, just slightly different withdrawals. But if your panic disorder is that severe you probably should try looking into adding another drug to see if it will help.
One drug that is rarely prescribed these days is buspar. Now it obviously doesn't help everyone, but it works completely different than SSRIs and so much more gentle on the body and easier to withdraw from if you ever wanted to. Buspar is the only drug in its class made specifically for anxiety.
That's one you could try and it wouldn't be as awful as starting an SSRI. There is also Wellbutrin which could be worth a try although it is stimulating to a lot of people and Remeron. The wellbutrin and remeron won't kill your sex drive as much, but the withdrawal from remeron will probably be equally as severe as the ssris.
How much therapy have you actually done? You may need to keep looking for a therapist that will actually help. Some simply aren't as good. You also have to really force yourself to go and really try hard. Psychotherapy can be effective as medication, but it does take tremendous effort and you can't give up. You have to keep fighting hard to get better. I am currently in therapy and I go once a week. It's very hard sometimes because I am so anxious. I can barely leave the house, much less drive anymore. But every Thursday I force myself to get to the therapist office. I shake, cry, tremble, and pour sweat in the waiting room. I am just refusing to give up.