hi Popping candy,
I'm loving these analogies. You're not selfish, you're struggling, and that's totally to be expected because you're human. Ps the analogies aren't sadistic, depression is. And it's a disease, not an aspect of personality so I think it's ok to separate them out and tell depression to eff off once in a while.
My partner suffers with severe anxiety and I've told him once or twice that I love him, he is a wonderful person, but I hate his anxiety because of what it does to him, he knows I'm not talking about him, he knows that like any other illness, it's understandable we want the illnesses, not the people, to bugger off to a hole in the ground. If anxiety was Hans from Die Hard I would push it off a New York building then go celebrate Christmas.
I'm really sorry your anxiety is also so hard, I hope you can find the strength to talk to your partner because being honest about how this is affecting you could be really good for both of you and your relationship. Neither of you has to go through it alone. If it feels like something that might help, could you talk to a councillor, maybe together with relate?
Hope that helps. xxx