Hi UpInTheTrees,
If you can look at the situation about the conflicting plans with as much objectivity as you can, you will see that it's not a catastrophe. You will beat yourself up a whole lot more than necessary. Your parents will get over it. Did they let you know ahead of time that they were preparing a special dinner? If they didn't, then your guilt is totally unnecessary. Even if they did, you didn't commit a felony; cut yourself some slack. You recognize that this has been something you've done in the past - that's the first step to doing better in the future.

My therapist told me there are only two things you ever need to know about your parents: 1. They did the best they could. 2. They f***ed it up.

I think that means we should be grateful for how hard they try and forgiving for their mistakes. I guess the same could be said about a child. I'm a grandma myself and I still have misunderstandings with my mom.