Hello Theresamary

I'm sorry for what has brought you here but I'm glad you found us.
It's understandable that you'd have a difficult time having compassion for your daughter when she's lashing out. Many parents here can relate to this, myself included.
Unfortunately, people with BPD (pwBPD) are driven by emotions rather than logic. Any attempt to point out that they may have a part in their suffering can open you up to verbal attacks, as you've likely discovered.
This does not mean you should walk on eggshells, but there are proven tools that can help you communicate with your older daughter, support your younger daughter, and take care of your own wellbeing, without feeling like you're taking sides.
A good place to start is the thread that's pinned to the top of this board: How to get the most out of this site
https://bpdfamily.com/message_board/index.php?topic=331689.0I'm sure others will be along shortly with links and insights, we are all here supporting each other along this journey.
You're not alone.
Again, welcome.
~ OH