I can relate to this because when my dad was ill (Not cancer, aneurysm of the brain), the company i worked for made it as difficult as possible for me to even attend hospital visits even during hours I was not working. For example, one night I was going to visit my dad at 6pm, and the hospital was 45 mins away, and i normally finished work at 5pm. So more than enough time to get there. However, on 3 occasions, a manager would arrive at my desk and would tell me i had to work until 5.30 or maybe even later. They had never done that before, but for some bizarre reason, they began doing it during this period. They were a relatively new management team that had been put in place, and they obviously wanted their own staff in rather than the staff who had been hired during the previous lot. anyway, come the 3rd time, i said no. I was only willing to work my contracted shift. So, yeah, one of the managers approached my desk and binned my previous work and said i had no choice.

Sorry for the language, but i just stood up and said **** it, and walked out. They shouted after me not to bother coming back if that was my attitude. Told them my family were more important, and I'd see them at a tribunal. Fast forward a few months and I took them to the cleaners. Hilariously, no one from the company turned up to the tribunal. That's how bad they were at hiding their constructive dismissals.

That was over 20 years ago. But sometimes in life you have to make a choice that best suits you. Only you can decide if you're willing to say enough is enough. It's a bad state of affairs that these things even happen, but as you have found out, there are some awful employers out there. They expect it to be all one way traffic. You to stick your neck out for them, but won't ever return the favour should you need them to be.