FMIL is stressing me out! Need opinions..Long, Sorry!

Background: FMIL and I get along great. But she isn't so nice to FH. She's actually his stepmom, (his mom passed away about 4 years ago) and they had a BAD relationship before FH and I started dating...and we all KNOW it's because she's happy he's leaving their house now and she can be a family with FFIL and her sons. She's already told us 'you can spend all the holidays with Diana's (my) family- we understand' ***! Fh wants to see his dad on holidays too!

So anyway, this weekend she drops the bombshell that she doesn't want to do the 'son/stepmother dance'. Fh was crushed! I stayed out of it and didn't say anything but that it was between them. For some reason after she left, I lost it. Was hysterical crying. It makes me soo sad that I'm going to dance with my dad, and he won't have anyone to dance with. He told his dad he wanted to dance with her..but his dad took FMIL's side and said if she doesn't want to, she shouldn't have to.

What should we do? Should he dance with my mom, who he even says is more of a mom to him that his stepmom will ever be? Or dance with his godmother- they aren't that close. I HAVE to dance with my dad, it's been my dream since I was little and we're very close!

There are quite a few other things she's done/said to piss me off about the wedding, but I'm keeping quiet..for now.

Thanks for listening and I'm sorry this is soo long!