What an absolute bitch. I agree she didn't meet friends, that was an engineered situation. If I really did meet friends that I didn't see much and was desperate to spend some time with I'd (and most people would) have said hi quickly and gone to meet you, or called and explained and invited you along. No-one normal or reasonable turns off their phone and gives no explanation while leaving you hanging.
What kind of support did you give her? I've heard ita quite common for people to ditch those who supported them through a really tough time, it's some kind of psychological thing when they start to feel a bit better, that their supporter reminds them of the bad time, or they're embarrassed as their supporter knows a lot of personal stuff about them and has seen them at their most vulnerable.
Agree that the other people haven't behaved great by not calling her out but a lot of people find that very difficult especially if it seems out of character and the group have always got on before, it can be so 'wtf' that people don't know how to tackle it. I also think it was very manipulative of her crying - if she told you to fuck off or something then people could tell her to behave or get out of the group, but if she is crying it will be all 'I'm entitled to my feelings, why are you all trying to force me to speak to someone that I'm deeply uncomfortable talking to' etc.
Please refer that she isn't a nice person trying to bully you out of the group. Most groups have people who don't like each other loads and wouldn't speak if it wasn't for the group - that's fine, most people can still manage to be polite, kind and have a civil conversation. Her leaving you hanging etc and her behaviour now shows she is an unkind, self centred, manipulative bully.
Please don't feel guilty about the effect on the group - it sounds like you don't want to go to things because of the atmosphere if you're there. It's her causing the drama and the atmosphere not you, so please don't feel guilty at all, you need to repeat in your head that she should feel guilty, you've done nothing wrong.
If anyone talks about it I'd just say you're as puzzled as they are, given she accepted so much support from you when she needed it and you spent a lot of time together including one on one. And say its fine if she doesn't like you but you don't think it's very fair to not even try and be civil, as its affecting the group.
I'd be mentally prepared if no one is calling her out on it though that they might think there is more to it or that they might 'not want to get involved' and have a separate WhatsApp group with her so that they can try and be 'fair' and spend time with both of you. If they do that and want to side with the bitch they're not worth bothering with. At least some of them have sent messages of support.
You're also just taking her behaviour, I'd consider trying some of her tactics and burst into tears when she blanks you / is curt with you. Why should you have to pretend that you're OK with her disgusting treatment of you, for fear of upsetting everyone else. You're the victim here but she is making it all about her feelings