I kicked my ex out after 8 years of lies, manipulation, steeling, cheating & drug relapses....ect. I had enough. I wanted to smile, breathe and laugh again. I wanted to care about my appearance, my family, my job again. I am sure that these are some of the things that are going through your brothers ex girlfriends mind.
I am sure that she still struggles with all of this, and about your brother too. Just because she is possibly seeing someone else does not mean that she does not care about him still. People have different ways of trying to forget and move on.
How are you handling all of this?