When people show you who they are, believe them.
She has shown you for years that she is a taker and a user. You keep being generous and reaching out, but it's not reciprocal.
So while your feelings are completely understandable - you had a family emergency and she wasn't there for you - I think you are more disappointed than hurt. She's never given to you, so it's not like she's taking something away now. What you are losing is not the friendship, but the HOPE for a friendship that you have cultivated for years. It just never bloomed.
If she called when my son was so injured, there's no way I'd have spent 45 minutes on the phone with her. I'd have said, "I'm sorry, but Jimmy and I just got home from the ER, and he needs me. Talk to you another time. Bye."
Don't call her. Not because she told you not to, but because she is not, and has never been, your friend.
Cultivate some friendships with others in your neighborhood or among your children's friends' parents. You've missed out on some terrific, giving people by devoting years to this woman.
And why did you put in the part about changing your name because she has an account here? That's waving a red cape in front of the bull. From the high level of detail in your post, it's very clear that she will know you are talking about her if she reads this. If you think this will wake her up and make her change her ways or apologize, I think you are still having fantasies that somehow this relationship can change. It cannot.
The only thing you've done 'wrong' here is to assume she would reciprocate if only you did enough to 'deserve' it. But she's not like you. Don't let someone so selfish hurt your feelings. Don't think she can change her ways. The only things that can change here are your attitude toward her and your actions. Don't waste another second letting her wear on you. If you stay hurt, you keep putting energy into this relationship, which has no hope of being more than it has been.
Ignore her, don't answer her calls, unfriend her from Facebook, don't offer to pick up her grandkid, don't save another piece of hand-me-down clothing, nothing. Don't pick a fight, but don't invite one either. You know those annoying telemarketers you just hang up on? Same thing here. Invest nothing more than you have already. Somewhere there are some terrific people who would love to have someone like you as a friend.