An Unattractive, Redundant and Particularly Harmful Stage of Grief

I found a new stages of grief, broader than the 5-stage Elizabeth Kubler-Ross version.  I like it better, too, I think...especially for my situation.  I really couldn't comment on the traditional stages, as I've never lost someone infinitely precious to my daily life--at least not to death.  While I love my grandparents, it's not at all the same, you know.

However, I find myself still hit hard by emotions right now.  I'm out of kilter with the traditional stages, though.  I can identify better with the New Stages, which include only three:  1) numbness, sadness; 2) intense emotion, including depression or anger; 3) recovery.  

My grief not only encompasses my feelings around my grandfather's death, but grief for my sister's suffering.  On Monday, her boyfriend--her first serious boyfriend since she was widowed six years ago--had a seizure and died in her arms.  He was only thirty.  She is completely heartbroken, and I feel her pain so much.  I immediately went to be with her and witnessed her heartache.  So, so much pain.  Life seems so unfair...and I haven't told you the tragic history...there's much more.  She shouldn't have to suffer so much, and he shouldn't have, either.  

That was overwhelming by itself.  In fact, I'd already entered the grief process there with her, for her.

Then, when Granddaddy died, that cemented it.  I felt my mind slow, numb with crying and sadness. 

I almost wish I could just stop it there and jump to recovery.  That seems, well, almost commendable, right?  It's appropriate to be sad at these incredibly sad events.  

However, I have quickly progressed to the intense emotion stage, and I'm incredibly sorry to say that manifests as ANGER.  No, not at the deceased--of course not.  It tends to land upon whoever behaves imperfectly at this time of heartache.  I am dealing with livid rage, honestly, and I'm noticing this is a pattern.  No, not anger at the same folks as at my grandmothers' funerals or my brother-in-law's funeral.  While I haven't done anything with my current rage, except vent to my BFF, I'm a bit scared of attending the funeral.  What can I do with such intense emotion?  How do I handle this?  

Ideally, I want to be supportive.  I want to honor the deceased, to support the most deeply bereaved.  How do I let go of this anger?