Working ThroughVs Expressing Feelings

Which feelings should one “work through” and which feelings should one express? I am conflict-averse by nature so received wisdom holds that I should get better at asserting my boundaries. But in at least two instances in recent weeks, I swallowed my feelings and decided to digest them instead of expressing them, and thanked myself later for it. My feelings have been so volatile lately that I can’t trust them to stay in place long enough for me to act on them and not regret it. So what is to be done? Firstly, I might be using the terms feelings wrongly, at least according to some people. Emotions are mental states (sadness, jealousy, etc) while thoughts are interpretations of these mental states, and feelings are physical manifestations of those mental states. There is a lot of work out there urging people to pay attention to their “physical” feelings instead of getting swept up in emotions and thoughts. I read a book not that long ago titled Radical Acceptance, which has a central message of accepting every feeling without resistance and observing it instead of judging it. To pay attention to the parts of the body that feelings manifest as physical sensations. My problem is all my feelings seem to emanate from the  right lower abdomen. And, I am not sure how that knowledge helps.