At the start of parental alienation, even before you are aware of it even existing, do not try to cope with this alone.
When I was splitting up the situation was so subliminally toxic (i.e. I didn’t realise in what a sh*t situation I was in) that I needed to talk often, practically daily just to try and understand what was going on. The only family I had were my sons, then 7 & 5 which of course I couldn’t talk to, so I turned to my friends that were absolutely amazing. I cannot remember a time when they turned me away on the phone, or said that I was getting on their nerves.
What everyone needs in this situation is a personal support network, not only groups of like-minded people but also friends available practically 24/7.
One point I would like to make here is that you are, surprise surprise not always right! I remember back to my time that I was fighting the good fight, and I had fairness and justice on my side. That empowered me to perhaps write the odd e-mail I should not have (nothing nasty – not my style), perhaps reacted more sternly than I should have and more. The point is that friends and groups are there to help, they listen and give advice – take it!
To use a well-worn phrase one “Cannot see the wood for trees”. Somebody looking in from the outside can see the big picture and can give you better advice than you can give yourself.
Incidentally, if your ex is of the narcissistic variety then she will just do whatever she thinks is right without taking any advice. Which means logical arguments from you will not make the slightest bit of difference if it is against their way of doing things – for instance bringing up the children, splitting the household after the split etc.
If you are alone, or your friends are of the type “There but for the grace of God go I” type, then find some selp-help groups. Both in the UK and Germany there is help to be had.
So use your support network, take their advice. Learn that is it sometimes necessary to do follow someone else’s advice or just simply do nothing.