I'm going to ignore my ex-best friends cry for help
Why would you ignore your ex-best friend's cry for help?
I really don't care about their problems anymore.
You shouldn't ignore someone's cry for help. If the messages from her are bothering you and you can't help them anymore you should suggest that they see a professional.
I'm just going to block her messages so they don't bother me.
It sounds like she really needs help and you should tell someone close to her about the issues. I know you don't want to be bothered, but if something bad happens to her you would feel very guilty that you didn't help.