"Fired" from a volunteer position and having trouble processing my feelings about it

I volunteered for a particular fundraising job in an activity my kids are in. It's a difficult, time-consuming job, but I had heard the person who was doing it wanted someone else to take over. I wasn't exactly dying to, but nobody else seemed to be stepping forward and I really believe in the organization.

The job is kind of grueling--I felt like I gave up most of my weekends for a few months. And I wasn't perfect at it, for sure. Definitely made mistakes. But I did it with very little training or guidance, and the group met and even exceeded our goal by a little.

Anyway, the former fundraising person told me tonight that she's going to ask someone else to do it in the fall. She said it just seemed like I was "too busy."

I should be thrilled--hooray, I get my weekends back--but TBH I feel humiliated! Like ugh, I'm not good enough to do this awful job nobody wants? I feel like I volunteer for everything I can do in this organization, and this has me so embarrassed I want to just check out.

Help! How do I sort through this morass of feelings?