NO!! It is absolutely not selfish to want a break.
Carers are some of the most amazing people on the planet and they often forget to look after themselves.
If you don't take care of yourself too, it could lead to a position where you're no longer able to care for your family- meaning that your own health could start to decline.
When my mum was losing her fight to cancer, our family all pitched in to care for her so she could spend her last couple of weeks at home instead of a hospital. We all made sure we took turns leaving the house, even for an hour or so just to clear your head. Caring can be so intense and takes a huge toll on everyone involved.
If you're family are unable to help, maybe even get a hired carer in for a couple of hours a week just to give you that break. I think Anglicare offer that service : )
I would never take back caring for my mum and now that she's gone, I have no regrets about how we managed things.
I hope that helps
Keep up with your amazingness!!
Lots of love