@carpe_vitae One thing I would say is not to have too much of an agenda with investigation. Don’t be too eager to find the belief, moral or realisation that will be the answer that makes the pain go away. Allow these to surface naturally, experientially. Going too much into theory, even quite sensible ones is often a sign of avoidance and will ring hollow. It’s trying to wrap everything up before you’ve figured out what this thing you’ve got is. Seeing the silliness is more like a genuine and somewhat surprised laugh to a good joke, and less a matter of deciding in advance which joke you will laugh at.
Adopt an attitude of naivete, curiosity, fascination and openness. Feel your way in a spirit of exploration and try and have fun with it to the extent possible - as opposed to trying to defuse it ASAP. Map it out slowly like some seaman charting a new course through some unexplored waters.
Don’t tell yourself off for feeling something. I mean you are a feeling being. What else would you do with yourself? 
Just feel it like it is happening for the first time and there is no one watching you. To feel intense jealousy, especially when you’ve been cheated on before is the most understandable thing in the world.
If you feel strong shame and helplessness with an emotion it might be time to give it a rest. Often investigation about hot trigger themes will blow up in your face - repeatedly. If you go past the pain point, you’ll just be overwhelmed and suffering instead of investigating really. Better to go back to neutral first or take a break and revisit it once you regain your composure.