Trying to control outcomes

Hi Brooke

I found out today that an ex-coworker of mine is trying to poach two people from my team to go and work with him. He has been planning this for a long time and it may not eventuate but my brain is going crazy thinking of ways to stop / control him.
Part of me things as a loyalty to my workplace I should tell my boss, but then I feel like I’m trying to control outcomes for my own benefit. My models today are below.

Unintentional Model
C Ex coworker organising job interviews
T They are all going to work together without me
F Left out, sad
A Tell my manager, try and get in their ears about not leaving
R Stress that they will leave and all be together

Intentional Model
C Ex co-worker organising job interviews
T This has been going on for over a year
F Indifference
A Let him do what he wants to do
R Acknowledge it may or may not happen

I am really struggling with letting people do what they want to do, even though I know I can’t control that! Any advice? Thanks so much.