My friend has let me down when I've really needed her. She is now asking for my help. What should I do?
You are clearly undecided about the correct behaviour between friends.
If you choose to view your relationship with your friend as transactional, then she has run up a large debt and does not have a promising record of reciprocation for kindness.
If you view the situation as an opportunity to honour your values, you may ask yourself if you choose to be a person who holds grudges or acts vengefully when you are short- changed. Alternatively, you may choose to practise being a bigger person, extending your capacity to show love and kindness even when someone may not deserve it. What you need to remember is that what you choose to be today aggregates into the person you will become in the future. You must be clear about who you would prefer that person to be. - Leonard Carr
The deeper question is: is this a friendship or an acquaintance? What do you value about your connection to this person? It is unrealistic for one person to be leaned on at all times for everything.
If you value your friendship, go the extra mile and see her through this tough time - leading by example. When she is more settled after this event, and you want to build the relationship on trust, tell her you are feeling hurt about her lack of support. You should be able to tell her this without threatening the friendship. - Stephanie Dawson-Dosser