Hello and welcome. Glad you found your way to talk with others who have been in similar situations. I find it does help reading other stories and seeing the various coping mechanisms.
Finding your depression is spiraling is a worrying development. Have you told your doctor about this? Can you talk to him/her about a referral to a psychiatrist? I suggest a psychiatrist as their fees always have a Medicare rebate and they can prescribe medication. It may be you need a change of meds though this is up to your treating medical team. If you have a Mental Health Plan from your GP you can see a psychologist for ten sessions per year and get a Medicare rebate. After that you are responsible for the whole fee. Why not have a chat with your GP about this.
When I became depressed 19 years ago I felt pretty much the way you have described above. Constant sick days and a boss who was a bit of a bully. Like you I could hardly get out of bed and was constantly tired. Being depressed is hard on your body as well as your mind. Not wanting any interactions with friends and family is fairly typical of anxiety and depression. The sad part about it that you do benefit more by being with people and having the stimulation to think about things other than your mental health.
I used to make myself attend the social functions I once enjoyed but I often felt like running away when I was with others. Crazy eh? This is indeed our unwellness messing with our brains. Our brains are clever as we can think about and believe in two opposite points of view.
Do you know much about depression and anxiety other your own experiences? I suggest you browse the information provided by beyond blue. Look under The Facts and Get Support above. You can download the fact sheets.
Can you take leave for several months from work? I appreciate this may not be financially possible. If you see a mental health professional discuss this with him/her first. I know this is what my psychiatrist wanted me to do but I did not have enough accrued leave. He also wanted me to go into hospital but at that time I did not have private medical insurance. I was surprised to realise I would have gone into hospital quite readily because I believe I would have thought I was safe there.
Also the thought of being on own every day was scary. There are the two opposite points of view. One tells us not socialising is good while the other argument finds being totally alone horrifying.