hi
@Stayingalive
you might also try going out of the room, changing your clothes a little eg different, very old jumper, then calling through the door of the room 'hey it's(your name), (his name), I've got a coffee (or some treat) for us' then slowly enter the room with a smile and put the coffee next to him ... keep your behaviour low key, eg no pet names or touching him, sit in another chair and be very still, so you can assess how he is reacting, if negatively then need the loo and leave him be ... my dad seemed to clue in to my voice as long as he heard me before he saw me and it helped him orientate himself to me
you might even quietly put your coat on, go outside then come in calling to him in a cheerful way that you just had to pop out but you're back now and how about a cuppa ...
and have an excuse ready to cover why the other woman has left ... something vague and simple and immediately change the subject
doesn't always work but worth a try?
I probably wouldn't try explaining or showing photos as your husband won't, at that time, be able to shift his thinking ... I doubt you would react well to someone trying to convince you that he is your husband when you know he's not, which sadly is how it is at that time for your husband