What I do know something about is constant suffering which you are forced to live with. You can drink yourself stupid, shout at the heavens, bang your head against the wall - but when you wake up in the morning the pain and loss is still there. And in the end there is nothing you can do except breathe - yeah, just carrying on living is a small act of resistance.
At the risk of making it worse than it already is, it may be that you have to accept an ending. As awful as it is, it does have the effect of stemming the bleeding and allowing the long slow process of healing to start. I dunno, I don’t know what’s going on. But you have to survive - that’s the baseline. Which means making your way forward one day at a time. Do some work, any work. Write some music. Pain and art are good companions. Don’t hold your breath waiting to hear anything from God. But there may be the odd glimpse when your heart is crushed that you’re breathing your way into the core experience at the heart of it all - a combination of love and powerlessness.