I don't know if I have the best answer for your situation, but there are points in time when you have to stand up for your beliefs and values. DB doesn't mean letting someone walk all over you...why would they want to be with that kind of person? that's not attractive, to do whatever they want. Perhaps you could come up with a constructive way of approaching her about the 2nd going away, point your thoughts there instead of continuing to be angry with her...that won't change, but YOU can change the way you approach it. Rehearse it in your head, as to what she MIGHT say and then how you could understanding. Like "I understand you need to get away with friends and be good to yourself but..." then if she says "why do you care what I do" rehearse what you might say in a positive way back...
See where I'm going? It won't help to continue to be angry with her choices, you can't control her right now, but you can choose more positive ways to react.
I hope this helps your sitch, if not maybe it will guide you in the right direction.
Pud
Me:49 H:47 S: 16 T:27 M:25 My EA: 2001 His PA: 10/2007, 6/2013 Separated, but H still in house
Find your Shambala: a place of peace and happiness.