Just behave normally.
What role would you like to play in her life now?
You can continue what you are doing but i will suggest you don't
go overboard with getting too close to her if you would
like to stay as a good friend cos being too over might make her
feel uneasy especially if shes still thinking of her ex.
Its fine to wait for her at times but maybe not all the time so
that she still has some 'space' for her ownself. Messaging and
chatting with her is fine since friends do that anyway.
Study hard and do well for your exams. If she does care
about you, she won't want her actions to affect your well being or
your academic work.