Hi Grace,
That sounds like a pretty upsetting dream; I would have had a strong reaction too! I hope sharing it helped lessen its impact, even a little. If you're looking for an analysis, I'm afraid I'm unqualified to give an official one, but I would suggest working through some of the questions I mention in the post and thinking about your relationships with your mother and grandmother. Dreams like this are rarely literal, in my experience; usually they're a representation (often an exaggerated one) of things we've been experiencing and thinking about on a subconscious level. If you have a history of SH, it may relate to that; if not, and if you've had no desire to SH during your waking life, it may be more about some things you may need to vent or confront that actually have nothing at all to do with SH -- but *do* impact your mental health.
I'm sorry I have to be so vague! I hope this helps anyway. Take care!
-Kim