Really, really sorry to hear you're going through that mate. I can relate to most of it, though, for what it's worth. It's like things tend to slowly fall away isn't it? It's as though your world slowly becomes a smaller place, things fall away until you're just a single point of life - existing - just breathing and experiencing, being alive, but that's all.
I used to play rugby, but stopped, I used to box but that stopped. I recently stopped going to the gym to lift heavy, and used to do a tonne of conditioning, although that's all slipped away fairly recently so I'm still pretty big and in shape for the time being - that too will change no doubt.
Also, now, certain things that I used to derive enjoyment from, I can't even face because they remind me of certain things, certain people, times, situations, the past, regrets, things I've lost, all sorts really.
So I haven't only lost enjoyment from them, but even the very thought of doing them, and thinking about it causing me to ruminate on things stops me even attempting them in the first place. If that makes sense?
I used to love reading, but aside from a very few select things, I can't. I can't watch anything apart from bits relating to an ever decreasing pool of subjects I've been interested in over the years. Music? The pool of choice that I can tolerate is getting smaller by the day.
Currently I push myself to do the things I know I must - anything related to hygiene, keeping the place tidy, doing the washing and so on. But I do have to make myself do it, which is nothing more than self discipline now I think. I used to absolutely love cooking good food, but now I eat the basic minimum, sometimes eating one small meal a day. I can't even stand the thought of making something dapper in the kitchen.
I could go on, but as you can see, I definitely empathise with you. Fun it ain't