Things happen, and sometimes we can't be three for the people we care about. It's ok. You don't sound like you ignored her on purpose, she's just hurting. You seem to be hurting along with her. you slipped up with the si, but you can move past that. You can also talk to your friend and be there for her now (or whenever she gets past her anger if she is not talking to you at the moment).
The suicidal thinking I would suggest reaching out about. There clearly more stuff bothering you, and it may be good to address with your t if you have one. If not, reach out to a hotline, and try to get some help around it. Finding a therapist to talk to if you don't already have one might be a good idea.