When to process vs not engage with emotions

I am learning with my past breakup (C) that I find being sad very comforting… I am also learning that it doesn’t serve me to indulge in it. I am wondering how to know when it is important to process an emotion while also learning how to not indulge. I notice a hang up in my mind when I am trying to tell myself, no I won’t be sad. It looks like this:

C: I tell my brain we are done being sad while thinking of ex at store
T: I should be allowing my feelings not pushing them away
F: confused
A: I indulge in confusion. I try not to decide. I judge myself for trying to stop myself. I decide to avoid.
R: I push my feelings away