I just feel so sad. Just been on a walk and all families are enjoying their time away in their caravans. Wished I could join a different family.
Thats so miserable for you.
Being Stuck in the middle.
Could you stay on and enjoy the place you are in? Maybe going on trips just yourself and your mum whilst both sides cool down?
Could you, or would you want to? go home with your Mum and spend a few days together there?
But you say she spent your childhood sobbing. Do you need to get away from all of them for some peace of mind?
Its "tumultuous and has been getting worse"
Are you usually the peacemaker?
If so, there's probably not much you can do but be a sponge to soak up their anger.
Is that a role? I've been there and it is a thankless task.
It may seem harsh, but I think in this situation you should really think about what YOU would rather do - all other things being equal - because it really is true that you can't please everyone in this situation so you may as well please yourself. If they are the type to take offense regularly, then they will enjoy taking offense anyway. So once you have made your decision. Put your foot down calmly and politely and act on it.
I'd also add being in a family war zone, you need to start putting yourself first and foremost and making firm plans for how you spend your time somewhere away from that, because spending it like this isn't going to do you any good at all.
You don't have to be on holiday with people to spend quality time with them. You could in future, organise your own holidays doing some kind of activity or with friends, and visit your mum and or sister separately for a short period of time, for example ( and I would plan activites for this time on the grounds that keeping them busy might distract them from their arguments. )
If you do go home, could you find some nice outings, or treats to do in your own hometown or day trips so that your time off isn't a total loss?
Lots of decisions to make. But remember just because they are tumultuous doesn't mean you have to keep putting up with it. Best of luck