This. If you're sure you don't want to be friends then no reasons for torturing yourself by thinking about her. I'd say your fear could be justified if she was violent and you could really be afraid she'd attack you. What are the facts? Did she do something like that in the past? To whom (her kids have different relationship with her than other people).

I think you could do what you feel you need to. If you aren't interested in the friendship, you can ignore her. If you feel just hurt but deep inside you want at least proper relationship with her, just act normally and accept she initially might not react as you would like to.

I think she felt guilty and this was the reason for her reaction. You aren't responsible for her emotions and reaction. But if you want you can act normally. Say her "hello" when you meet her. Just let her know that it does hurt you but it doesn't have to be the end of the world.