How I let go of resentment

I was irritated when my neighbour responded vaguely to an invitation to the community event I’d organised.
I resented her ability to be non-committal.
When asked to organise the event at a particularly busy time, I’d felt the need to commit. What I hadn’t allowed myself to say "this is a busy time for me. Thank you for asking, and no".
I’d negated my own needs and truth, and given a ‘yes’ based on the fear of losing the image of a dependable friend.
What started as resentment became admiration and gratitude; the next time I was asked to do something I didn't want to, I was able to give an honest no.