I'd strongly suggest telling someone how you are feeling if you have not already. I've been there myself where my significant other was having physical health issues and I was just spent emotionally, physically and financially. That discussion with my spouse and family was a big turning point for all of us for the better.
You don't abandon family.
Then again I'm Asian so perhaps our sense of family is different. For example, we often treat our cousins like siblings.
I'm not saying that we should run away at the first sign of mental health issues. I just think that there are plenty of situations where it might be the right decision. It's obvious in extreme cases, but the decision will always be extremely difficult.
For what it's worth, I think most people view their spouse as "family". It's hard to imagine a different arrangement.