@sallycream
Enjoy your day at the races. Ignore him totally if you can.
If he moans about his ear, say happily ''Oh dear, well..........it can't be that bad, or you'd have taken pain killers, or better yet, you'd have paid to get it sorted wouldn't you ? Oh, now did you happen to see what the name of that horse was ?''
Going forward, you'll only need to decide whether you'd be happier leaving him and divorcing, or staying as a couple, but never, ever, inviting him on another day out/ occasion meal/ birthday treat.
But if you decide that you'd rather just have a separate social calendar, don't specifically tell him. Just make your own arrangements, and let him find out when you're going out the door......
i.e
You - ''I've booked a day out to the Safari Park for this Saturday''
Him - '' You know I don't like animals.....and my ear has been playing up too.....''
You '' Mmmm, having a sore ear isn't nice, I know !''
Come Saturday....
Him- '' I think my ear is too sore for me to go today....''
You - ''Is it ? Why don't you take some Paracetamol ?''
Cue some more moaning etc, but keep saying non-comittal responses like Oh...........Hmmm..............I know...........Well then etc
Then when it's time to leave, grab your jacket and call out
''That's me off out now ! See you later ! Bye !'' (and turn your mobile off !)