Yes. That's what I would be asking him. He's doing competitive skiing with you, because he probably can't beat the rest of the guys in his group and wants to be superior to someone. He sounds really insecure.
Book a group morning lesson and ski solo for a bit in the afternoon.
I lost form returning to skiing after a gap... DH hurtles down with no technique on the brink of an accident, so he wasn't going to be much help teaching me
It could be something simple and fixable that's holding you back, the instructor will spot it in an instant. I nearly gave up but booked into a small morning group.
The instructor took one look and said "Ski technology has improved since you last skied." He adjusted my boots, with a heel screw etc I'd not even noticed.. And suddenly I could ski properly again.. Not brilliantly but I could manage.
For your own sake, get some lessons... ( by the end of the week you'll be showing the rest of the group that any comments he's been making are unfair and unjustified. ) It was an amazing overall confidence boost to get my ski legs back and not just in skiing.
Apart from that, Ignoring you in private whilst being over charming to everyone else in public to enforce the contrast is one of the shittiest and most overly punishing moves ever. A very nasty to keep it going throughout the holiday.
Logistically, it will be difficult/pricey getting down the mountain range in a transfer to the airport mid holiday, depending on where your resort is. And it will probably make things hard for DD. And he'd go on an immediate sympathy drive citing your "unreasonableness". So I would tough it out if you can.
How to survive the week if you have to stay on and he's still trying to punish you? The others will start noticing his behaviour. He wants you upset and cowed so I'd act as though his "ignoring" behaviour was utterly normal from such a manchild and so pathetic it's not worth acknowledging. He wants to wrong foot you, so that the rest of the group think you are difficult and moody - because he's so charming to them right?
I'd give a bright and breezy superior Good Morning as if to a sulky child and crack on cheerfully with my day, generally showing him that no input from him is required as his behaviour is not going to spoil your break. He won't know what to do with that.
Or not... Not everyone will agree with that approach. It's the one I've used with difficult people in fixed situations but it may not work for you. It depends what you feel will get you through the week.
Try to enjoy your ski mornings. Visit a spa or relax in the hot tub if there is one, or have a facial, enjoy your DD's company Take the time to Have a nice coffee contemplating the glorious views and and think about your possible options you can act on when you return. Best of luck.