Firstly, Please don't apologise for posting. That's why we're here, right? Work sounds extremely stressful right now and i can imagine it's extremely difficult having that happen to somebody so close. Understanding somebody is hurting is hard at the best of times but with other things going on too it can't be easy. The truth is, she didn't 'succeed'? If anything, does that not say that she's not ready to leave just yet? You mention you've never mentioned anything to your collegues though could this possibly be an oppertunity for you to support this other person through your own experience? Opening up isn't easy though another option could possibly be to try and influence people around her to deal with this the way you wish they would deal with it if you were her?
Simple things like not asking questions people don't always understand but if you could somehow prevent this, in turn you will be helping her... Hopefully, she'll be recieving the right support now though ensuring she knows she isn't alone could be important if you feel comefortable with this? Please remember, you are just as important and you are in no way responsible so try not to punish yourself or think about it too hard...
As for your auntie and uncle, break ups are never easy though one way to look at is that atleast it's happend now? They could have pretended things were okay for much longer which could have only made things hurt most... Also, use protecting and caring for your cousins as a distractions from all the other things.
Alot of this is easier said than done, but you are not alone!
I hope something i've said comes of some use!
Please stay strong, Kia <3