How does one "let go" of another person who is still an integral part of one's life?

I’m in a delicate situation, and I need assistance to understand the best way to handle it.

I am highly active in community theatre. I just opened a play I co-directed with the local university’s drama professor. I act, too. I sit on the board of directors for the community theatre organization, and I am a past president of that board.

My ex-wife, the mother of my children, is also active in the theatre organization. She also sits on the board of directors and is the current president of the board.

She is an actor in the play we just opened, and she came under my direction. She took some direction well, but then she openly questioned my ideas and by extension my abilities.

At opening night yesterday, she would not look at me before the show. We passed each other numerous times backstage, and she never acknowledged me while she did address other people present.

After the show, I approached and congratulated her on a good performance. She thanked me. I invited her to go with the large group of actors to a local diner for a late dinner. She accepted. Two of our children were there, too.

Last summer, I submitted and received approval from the board of directors of the theatre organization to direct our group’s Shakespeare in the Park for next summer. When it was approved, my ex spoke in favor of the idea I put forth. Since then, she has publicly criticized my concept several times. She did so last night at dinner after the show. I was forced into a position in front of other actors to defend my concept.

Our relationship, as with any divorced couple, is an odd one. We live in a small town. We know the same people. We are active in groups together. We have children together. One child lives with me full-time, and the other comes on weekends.

Over the past weeks, I have been criticized by her privately and publicly about my theatre work. It hurts. My best friend has advised me to “let go” of her, but I don’t seem to know how to do that.

Do you have experience “letting go” of a person who is still an important part of your life? If so, I’d love to hear about it.