Oh no no no no....no.
OP- it's not like you 2 are going to Cancun or something. This is Disneyland!
No child would ever understand why Mommy & Daddy went without them....imagine how hurt they will be. And the fact that you are going to WDW in the near future will be no consolation.
When I was about 13 my Mom went to WDW on a business trip. She was a
travel agent and got to go on "fam trip" all the time. I was beside myself because I simply could NOT understand why she didn't take us all with her.

Yes, she sent us postcards (which just rubbed it in further!) and she brought us back nice gifts (which made me feel left out) and really tried to make us feel ok about it...but to be honest, at the time- I wish she had never told us where she went. As a kid, it would have been SO much easier had I never known what I was missing out on.
Of course now that I'm an adult, I totally get that she didn't choose to go all by herself to WDW. This was a legit business trip and now that I'm older, I can laugh at how silly my 13 yr old self was. But let me tell you...at the time, I was very upset with her.