Worry/Fear of the future

I woke up with a lot of thoughts this morning. I sat down to do a quick self-coaching and I identified my primary thought to be
– My manager might quit and this would delay my promotion.

My manager and I are working on my promotion. We initially target for Mar 2020, now due to some deadline changes, we decided to push it to July 2020. It was announced that a manager from another team is moving on. Following is my unintentional model

C: Manager x from team y is moving on
T: My manager might quit and this would delay my promotion.
F: Anxious
A: Worry. somehow prevent this from happening. Ruminate. Avoid this thought, tell myself it won’t happen, but brain won’t believe it.
R: I quit (mentally) irrespective of what happens

I see that I am creating anxiety for myself because my brain says a terrible thing might happen in the future and somehow we need to prevent it. My brain wants to avoid the future feelings of disappointment, shame, regret that I would create with my own thoughts like below if in case the circumstance comes true.

Model my brain wants to prevent from happening.
C: Manager quits
T: See, you knew this, it’s all over.
F: Disappointment
A: Beat myself up. Tell myself I should’ve quit before, found a new job or did something to secure my promotion.
R: I make it the end of all good things.

The truth is I can really prevent that above model from happening, but thinking ahead of time, what would I make his quitting mean, if that does come true.
Some thoughts that I can commit to practicing are –
1. I can do negative feelings. They are just created by sentences in my brain. They are harmless and they are optional.
2. Manager quitting is a 100% neutral and it is just a circumstance.

What are some other thoughts to practice? how else can I coach myself here?