I'm so sorry for all you are dealing with. I wish I had some magic words of wisdom, but I surely don't. It seems you are doing all the right things, seeking out the help you need. I think you just need to give it more time. And agree with others that finding some other outdoor activity (when it is less cold) that can get you moving and enjoying fresh air, might help bridge you over until you are ready to ride again. I know all too well how much not being active and not getting fresh air can adversely impact how you feel. And I'm not dealing with 1/100th of the sadness you are.
Be kind to yourself and don't expect too much. And come here for support anytime. We'd all take that pain away from you in a second if we could.