I don't think there's a "well" way of handling that kind of loss but you should really bring it up to her. It's unfair to other people to be the landing spot for everything she's feeling. Any support groups in her area? Does she talk to you that way too?
I've tried to but she loves deflecting. "Sorry, I just had a bad day at work" is her favorite excuse. She treats everyone that way, my dad.. my brother who is mentally challenged and the way she talks to him sometimes really pisses me off because he's "slow" and she has zero patience with him. I've tried bringing it up to her but she takes no personal responsibility for why she treats people the way she does what so ever and gets really defensive and acts like a child who didn't get the toy he wants. And I'm as nice as possible about it too.. I could say "You know, I think you should talk to Jeff a little nicer " and she'll turn into how I should quit smokin and get friends
She has a lot of resentments I think and should definitely seek a therapist, but she never will. She's the most stubborn emotionally timid women I've ever met.