At breaking point caregiving w/full time job

My partner was diagnosed with State IV non-smoker's NSCLC in fall of 2015 - we have been together since 2013, he is 42 and I am 32. He has been receiving gene targeted therapies and radiation as treatments, most recently whole brain radiation for some brain mets. He is tolerating the treatments fairly well other than some severe fatigue and occasional nausea bouts.

Throughout his treatment, I have been working full time at a desk job. It pays well and has decent benefits, but it's incredibly boring and unfulfilling to the point of being frustrating. It is also increasingly hard for me to focus on my tasks and be away from my partner - his mother has come to visit during his more critical treatments and tests, but she can't be here all the time and I have had to stay home or come home early some days when he isn't doing as well.

My dilemma at the moment is seriously questioning whether I should quit my job. I am experiencing a lot of anxiety, depression and agitation when I am at work, and I am also concerned that my partner's time may be growing short. His most recent test shows that the current gene targeted pill has stopped slowing the disease progression and he seems sicker and more frail since the brain radiation. There are trips we want to take that I worry he will not be well enough to go on if I have to wait until I have enough vacation time at work.

I am fortunate enough to not have any debt currently and a fair amount of savings to keep paying bills and rent for the time being, so I don't think it would be catastrophic financially to quit even with having to pay my own insurance premium, etc. But there is also a part of me that is scared to quit because I know how fast savings can go if you're not bringing in income, and I don't want to endanger my financial stability. My job is at a company that is very stable and growing, so even though I hate it, part of me is afraid of throwing that away. I have thought about supplementing income with part time or freelance work to mitigate these risks. But it's still scary...

So I guess I am just looking for advice or personal experiences with quitting a full time job to be a caregiver for a loved one. Does it seem to make sense for me to do that? I worry that if his cancer worsens over a long period of time, I won't be able to take another job because of the stress and run out of savings. But I also don't want to be away from him so much and miss out on precious time we could be spending making however long he has memorable and happy.