Squirmy, very pleased you have been able to offer so much support for your friend, and sorry that it has caused you so much upset.
Are you perhaps 'collecting' upset from her, by which I mean feeling all her upset and wanting to be strong for her, and then breaking up once you are on your own? Also, it sounds very much as if you are thinking a bit of 'if that was me...' and reacting as if it was your pregnancy.
The one thing I have learned since becoming a Mum is that it really really should ONLY be done by those who are 110% up for it. Nothing less, no 'oughts', 'shoulds', no examples of other people's joy or other people's expectations of being a grandparent or aunt, none of these are enough to carry someone through the enormous challenge of being a parent. We cannot transform our own joy of parenthood into someone else's dream. Wait with your friend, support her, care for her, and maybe at some other time and place in her life, she will share (again?) the joy of parenthood, as plenty of other MN mums have done after an earlier termination.
It has been an emotional roller coaster for both of you, you have been sharing her journey; of course you are upset. Is there someone who can look after you a little bit tonight?