Hi Dandelion and welcome! Glad you feel this could be a safe space for you x
The fact that you are now becoming overwhelmed by stuff could - perversely enough - be because you've come through years of therapy, you've broken the abusive relationship pattern and you feel safer. I'm going through something a bit similar - it's like when you've had a cold threatening for ages, but you're working hard and then as soon as you take a couple of days off, it's as if your body goes 'okay, I can be ill now!'.
When you were a kid, the only way to cope was to find a way of living with your brother and having a relationship with him and the rest of your family, in spite of what he'd done. Now that you're in a healthier place, your mind is rebelling against this conflict (you don't want to see him, yet you still do).
Maybe it's time to find a new way of dealing with things? You don't have to have a relationship with your brother now, or any other member of your family. Maybe don't contact them for a while, give yourself space to think about what you want.
And welcome back, Don'tKnow - hope your DD is getting better. GPs are crap, aren't they - I had a blood test today, to find out why I'm feeling so ill, and I can't have an appointment to get the results until 17th May! Think I will just ring them every day until I get a phoner.