Against an armored psychopath in that environment, I'd say finding cover would be my first priority. Or getting my family to cover if they were with me. But, over all, it's kind of one of those things that you can't really plan for.
If I did find myself in a similar situation - using the tools I'd have on hand - I would think that lots of rounds directed at the neck region (COM high) would be as effective as anything. Hits to the chest are still going to hurt, and the neck/head are going to be less impact resistant even if you don't find seam.
si vis pacem para bellum