I was estranged from my mother, my sister informed me of her death, it was also in the local papers although I am no longer in the same area so would not have seen it- happened about 10 years ago. Earlier this year my brother in law (husbands side of the family) died unexpectedly, it was only announced on facebook & as I am not on facebook we didn't get to hear about it,until an aquaintance told me. I think it depends on the family as to how and who they tell.
Another poster has suggested that you go to the funeral. I thought long and hard about going to my estranged mothers funeral, my inclination was not to go. A close friend/colleague and my DH persuaded me to go, I wish I hadn't. Nothing that was said had any resonance with me, couldn't recognise the person they were talking about, experienced no emotion at all.
It is not easy when an estranged family member dies - I wish you well.