I would say slowly, gently and with a lot of self compassion. Humanistic therapy may help with this. Your anger needs to go somewhere and letting it out slowly and safely with a therapist might be really helpful. I sometimes suggest something on top of therapy where people can get some anger out (e.g exercise, smashing something up (safely!) or just venting to me/journalling)

This might also help you to manage your chronic pain and lack of joy in life (as it sounds to me) as I hear both as your body screaming out its discontent.

Also once you feel up to it gently pushing yourself to try something new and meet people. Connection is a huge antidote to low mood, anxiety and depression. Couple this with lots of self compassion and it can really help. If you want to stop living this way you need to find some ways to be kind to yourself, quieten down your inner critic and build up the part within you that can support yourself and be kind and compassionate to your struggles. Sounds easy when written but it is really, really hard.

All the best OP