Personally I would strongly suggest couples counseling on this matter. It's one thing when some really just isn't into something their partner enjoys, but you're saying it really hurts and that's a problem in my opinion.

If you guys work together with a counselor, you can probably find ways that both of you get what you want. Like instead of using a hand or paddle or whatever using something soft like a teddy bear or ... I dunno, you get my drift though. With a little help you guys should be able to find something that works for both of you.

Teddy Spankxkin?