I know it’s hard but stop wondering why you have depressing thoughts THAT JUST FEEDS INTO THE VICOUS CYCLE if you don’t want to think about lions tigers and bears( oh my) then you don’t tell yourself “I don’t want to think about lions tigers and bears” , you think about zebras. same here don’t beat yourself up over being depressed move on from the depressing feeling and don’t worry about WHY it happened just then try thinking about stuff that makes you feel good about yourself.
and don’t worry about abandoning the world around you. it is very possible that your social anxiety AND your depression are both symtoms of the same underlying problem , and working on one will positively affect the other issue . have a great yom tov and always keep smiling. we are all rooting for you!!