No, maybe not self esteem, but I don't see you putting much value on the efforts you are making, for a man who doesn't or cant reciprocate in some way. It is a good thing you are doing, but it is coming at a huge cost, your own life (not meaning you plan to harm yourself, but that you aren't able to make some changes to make your own life better). Instead you are choosing, imo, to value his life more than your own.

That's kind of what I did in a way, although it's a much different thing when it comes to a child rather than an s.o. Buttt, I was more concerned with my younger than myself, and that just doesn't work. Also concerned for an ex who treated me like absolute crap. Different situations, but the similarity I see is that you are not taking care of yourself. Since I began really thinking of myself lately, and what I need to do to feel better, I've improved a lot. I used to think this was selfish. I even knew it was not selfish to take care of my health, my own wants, but I decided I was not worth it.
Now I realize no matter how many faults I made with my kids, or ex, or bf, I have worth because I'm doing things that give me a feeling of usefulness.

And I think that is what you are doing. You feel useful, you are needed in this job with your s.o. So the dilemma is, do you stay where your depression worsens, and even when, sorry to mention, he passes, you are left in the situation you are in. Or do you begin to prepare your life for when he is gone? Sounds silly a bit, but me, I occasionally take out a pen and paper and draw. Even if its nothing much. It feels good. And the guitar, this is weird but now I want to be totally honest in the hopes of helping someone. I used to injure myself a bit, nothing major, but the pain made things more bearable in a weird way. Now I pick up the guitar, and the feelings I get through the fingers is enough to make me feel better. You need an outlet for your frustrations, and you are feeling bad that it is your s.o., but thats just natural for that to happen. He's right there, he's the source of your frustration, and then you feel bad that you ranted a bit. Don't.

My dad looked after my mom, almost soley, for years. She had Alzheimer's. She couldn't remember some days what was going on. I feel bad I wasn't there enough, but it is what it is now. He would leave when she was alseep and do his own thing. I sometimes thought "man, that isn't nice", but the reality was she wanted to sleep and he needed to get out. Just to Tim Horton's sometimes. He is friendly, talks to anyone he meets. He refused to go to church because he didn't feel good going without my mom. He really hurt when she passed. And a few months later, he carried on doing what he did before. And made a hard step going to church, with my son by his side, and even i (not liking churches), went. My point being, life goes on, and you must think of what you need to feel better. Sorry this was so long, must be the espresso I drink. Big hugs, you are in my thoughts.