I would like to thank everyone again for your advice. I talked to my supervisor and we agreed on me working remotely, so I was able to spend time with my mother while she still knew who I was. In the end, things moved faster than expected and she died in mid february. I spent some time with family and have started to go back to work a few days ago. A lot of people at my institute have been very kind but I am also reluctant to share too much personal information in the workplace so I am very glad about this forum where I could be open.

Thank you so much for your answers, writing about this situation already helps a bit. I have thought things over a bit more and with a clearer head, I am incredibly lucky to live in a place where healthcare is good and a nurse comes to my parents' home several times a day so there is not much more practical help I could currently provide. I am quite sure my dad would even disapprove of me suspending my PhD since it always has been very important for my parents (both of advanced age) that I am able to provide for myself and would add to his stress. The guilt I wrote about is more because I expect of myself to help in some way and I can mostly just stand by and watch. Taking long weekends off to visit in the next months seems a good option and maybe a few weeks when we know her health worsens. It should not be a huge problem to take unpaid leave but I cannot do that for too long since I depend on the salary (and I would probably go crazy without the sense of normalcy that going to work provides). I will discuss this with my supervisor to find a solution.

I am in need of advice in a tough situation. A month ago, my mother was diagnosed with an aggressive type of brain cancer. Since treatment would prolong her life only a few months, she will most probably die in the next 3-4 months.
I am now eight months into a competitive PhD program and was just making progress with my project. I do not want to drop out or take a break that is too long since I have dreamed of becoming a researcher since school. Work keeps me focused, but I also feel guilty about being several hundred kilometers away and not helping my dad with caregiving.
My primary supervisor is partially informed and very supportive, but I am wary about telling other members of my committe or colleagues. I have previously witnessed people in academia doubting the work of colleagues because "the person has emotional problems" (although that happened at my old institution, not my current one).