There is a lesson to be learnt in every situation... just sometimes the lessons are so painful that you just want to curl up in a ball and never get back up.
Anger is one of the stages that you go through... I've been there and it does go away.. it just feels like broken promises...
Time will heal you - let all the anger, frustration and sadness out.
One thing I learnt is that there are no answers to the questions... the questions remain and you just have to accept that sometimes there is no real reason.

Sorry I can't be more helpful - hugs to you

Always save a little bit of yourself for yourself... never give it all away no matter how special the relationship seems.