Im going to give my honest opinion here:

I would suggest that you try not to take things too personally.

I understand that you might feel hurt by her being more distant. But try seeing things from her point of view instead of making the situation about yourself. Be happy for her that she made amends with her mother. Be happy for her that she has a healthy relationship with your brother. Those are all good things that you should want for your friend.

Everyone has their own lives to live, you know? Just because your friend doesnt give you her attention every second doesnt mean that she doesnt value your friendship. Friends are supposed to be there for each other when they need each other. You were there for her during her time of need and im sure she appreciated that but you cant expect her to revolve her life around you. She has other people in her life, not just you.

Try developing some hobbies and broadening your friendships. I think you may find it easier to understand other peoples behavior as a result. You seem like a good, caring person with good intentions- you just need to understand yourself better. A good therapist will help you out with that! I wish you luck. Just give your friend some space in the mean time and I hope things can mend with you two soon!