Well I read it. The numerous deceased were not all unarmed. Some were and they were all attacking as a group in two separate groups - the first group had bottles and the second group had a knife in addition to the fact that they outnumbered the victim/shooter. Some of them sustained wounds to their backs or sides because they turned as the victim fired his shotgun in self defense after the groups initiated their attacks. All of these gang members that were initially described as victims before I read the article were actually assailants with intent to cause defendant great bodily harm, so the law was applied correctly!
I cannot see a ANYTHING in that case that is even REMOTELY similar to what OP did, so I cannot see it helping OP or being indicative in any way to what the outcome of the OP trial will be. I wish that I hadn't spent the time and energy reading it.
I read the first shootings the same way as you; the appeal court found all were assailants and therefore that the appellant shot in self defence (I am not sure I believe the shooter though!), but I think you have misread the second group. The appeal court upheld all three murder convictions handed down by the first court for the men the appellant shot at the house and the way I see it it does have some bearing on this case. The knife was for peeling potatoes which the victim was doing at the time the appellant arrived and the dog never attacked, nor did any of the others. The appeal court noted: "On the facts the appellant could not reasonably have believed that his life was in danger when he shot Hassan, Jacobs and Gouws. The convictions [murder] in respect of 5, 6 and 7, must, therefore, stand.
From that it appears OP should need more than just a belief, however genuine it was to him, to successfully claim imminent danger and reasonability to use deadly force against an unseen aggressor.