Very similar situation happened to me. We weren't even dating but srong connection was there. Everything seemed to be really good just like with you, friends, family etc. but her ex was always in the background and she had mental health problems too. And just one day before our friends wedding that we planned to go together, she just blocked my number and instagram. When I tried to talk to her she said that she just doesn't want anything, so I just left. So the real thing here is that she just wants her ex more than you, she still has feeling and emotional bond with him is probably stronger. But if it's ended one time, it's probably will end the second time and then she'll come back to you, just relax and try to use this pain to be better. What's really matters is when she'll come back, be really mindful about that, do you really need person who can discard you like a trash? That's what I asking myself. I'm on nc for a half of a year and even though it was so painful, now I really am happier than I ever was in my life, and I absolutely ok with her never contacting me again. I feel free and this is absolutely amazing feeling. Oh, and by the way, I'm pretty sure that she broke it off with her ex couple of monts ago and watching me online since than. This is how it goes. Hope that helps :)

What's her history with relationships?

Your mistake is talking with her everyday. In 5months she was already talking about having kids with you, that conversation is for couples who at least shared a year together. Your pace with her is too fast and she might be doing this as coping from her previous breakup. Just move on, she's blocked you. Nothing else you can do much, even if you bumped into her randomly it's her who should approach you since she blocked you