Discussing it with her prior might have been a good idea. While you were careful to build it as inexpensively as possible, that might not be what she’s upset about.
At this point, it’s done, so now you have to work on getting past it together. Communication is key.
Here are some relationship communication strategies when you have ADHD:
Penny
ADDitude Community Moderator, Author & Mentor on Parenting ADHD, Mom to teen w/ ADHD, LDs, and autism