The distinction between primary and secondary emotions is something I'm encountering during IC (for my FOO), too.
Disgust as a primary emotion is certain logical because I can't seem to pinpoint what other primary emotion it would be tied to. I'm no doctor or anything so this is just MHO.
I will outline a conversation with my IC. It's not verbatim but is a generalization of the actual session
IC: how did it make you feel when WSO didn't contact you for 1.5 months
ME: abandoned
IC: why?
ME: because I didn't feel loved anymore
IC: why?
ME: because I don't think he cares
IC: why?
ME: because he hit me with this shit out of the blue
IC: but how does that make you feel?
ME: abandoned and rejected
IC: why do you feel that way?
ME: (silence but then) I don't know
IC: you know why you don't know?
ME: (getting frustrated) No, I really don't know
IC: because you are in pain. But why are you in pain?
ME: (silence)
ME: (silence)
IC: TRD, don't fight your feelings, that is denial.say it out loud and be vulnerable
ME: because I hurt.
ME: I am sad
ME: I am afraid
ME: I am alone
IC: yes! that's the level you need to get to when you are experiencing emotions
ME: (now crying) but its painful
IC: yes but you need to go through it, not around it.
needless to say, it was a breakthrough for me. It relates back to FOO so that's what I'm working on.
he said some of the primary are: angry, sad, hurt, afraid, lonely, ashamed, happy
secondary would be more like: confused, upset, tense, good, bad, irritated....things you feel but don't really explain "why" you feel that way. there is an underlying reason
This is why I am so committed to working through my issues. I pray my marriage R but that will require two committed people who are fully engaged and eyes wide open...everything on the table. I can only control myself. So to get to the spot where I think I will NOT repeat MY mistakes of the past I must address my issues...and FOO issues are at the root of this.
^^^this^^^
I am on the same journey for myself and wish you peace. It is certainly an eye-opening experience.