It is so distressing to see, everyone who reads this feels for you.
Remembering the good times is always a good tip and knowing it is this awful disease and not really the person you knew so well.
Maybe you have previously prevented incidents like this when he was in your sole care?
Maybe the care home haven't quite got to know him so well yet. It is a learning curve.
But I would also be asking them how often they are checking on him and what plan they have to minimise the likelihood of it happening again.
It is so hard to keep it all together in such a situation, incidents might arise from time to time, so it will be very important to try and gain something positive for his care out of days like this.
Sending you love and the strength to carry on regardless