Disappointment doesn't usually lead one to jump to the topic of divorce.
At this very moment, I will confess, I am disappointed in my husband. No, he didn't do anything truly terrible, but he didn't live up to some expectations which, while I was mad about it this morning, I should have known I needed to convey better to him. He and Kiddo are out right now, but after they get home, after my husband gets a little break, I'm going to talk with him about it and figure out how we can work out a plan to help things be workable for me. (I've been suffering kidney stones for the past week and am dealing with a lot of pain. He's had a long week as well. Our communication hasn't been great.)
My guess: This, what I describe to you, is how you ward off a divorce. You give the other person the benefit of the doubt. You decide to talk to them in a way that is solution-oriented. For me, it's going to be spelling out what I am needing and what my abilities currently are when it comes to tasks.
One thing I will caution you about is being neither overly-dramatic or coming across as overly capable. I know I tend to do the latter. A couple years ago I was in the hospital for an appendectomy. I didn't want to-- and didn't need-- a lot of handholding. This Monday when we were waiting in the ER due to the pain I was having, Kiddo finally turned to my husband and asked "How long are we going to wait? I thought we were just dropping her off." I laughed at this. It's his -- and my husband's, no less-- experience of me, that I can 'handle' things which are very painful to deal with. What I'm saying is that you might also be in the habit of letting people believe you can do/manage more than you really want to, including the disappointment of the changed plans. Which means sitting down when you are both able to focus and saying, without judgment "You know, I am just not feeling very appreciated right now. I was disappointed that I made a lot of effort to arrange this and you didn't seem to remember. In the future, ___________________"(Insert your positive suggestion here : "please check with me" or "let's coordinate our calendars" or something that's progressive, not a lecture).
You preserve marriage by making the effort to talk about the hard things. I'm not going to say anything about how you should or shouldn't feel about your anniversary. What I will say is that if you are jumping to the thought of divorce, then you need to talk to the man because that IS a dramatic reaction. And that's not helpful for anyone--not you, your psyche, or your relationships--no one.
And I can tell you, because I homeschool now as well, J., you have to put yourself as a couple first. What the kids need most isn't necessarily time with Dad, it's to see Mom and Dad in a loving relationship on a day to day basis, and taking time for themselves as a couple. Otherwise, it's easy for our kids to forget they aren't the center of the universe, you know?