When am I "done" feeling / processing a feeling?

I realize I have a fundamental lack of understanding about *how* to feel a feeling.

1. So let’s say I have a Feeling and in that moment I notice the Thought that is causing it.
2. And so I notice the feeling, I see how it feels in my body, etc. But the brain immediately wants to jump to the next Thought.
3. And this next Thought produces a different Feeling
4. So do I go back to the original Thought? Trying to stay with it until the Feeling goes away or diminishes ? How do I know I have fully processed an emotion?