Hi Sarah,
the symptom here is inflammatory swelling around the ((Nervous - Trigeminus|trigeminal nerve)) on the right body side - your "partner side". This nerve is linked to the Social Engagement System and to skin sensitivity in the face, that's why it reacts to  triggers around social connection (inflammation and swelling in regeneration phase A, and especially when your energy battery needs recharging (sleep). The underlying conflict is about (not) being in safe, good company, where you feel seen, connected, and can talk freely (New Brain themes). You hardly ever feel at home anywhere (Seems to me like a chronic search to resolve ((Urinary - Kidneys - Collecting Tubules|abandonment)) ). Cats are triggers for connection but also for bad memories, so that's a two-edged sword!
So your "wild guess" seems correct to me, and it may be aggravated through some Old Brain being alone blueprint, if that makes sense?

Regarding resolution and healing these lifelong themes, yes it takes time and yes it is possible. The question is would it be ok for you to let tragedies be stories that you have honoured and grieved, to the extent that you have completed them? Not all stories need to have a happy end. But one can decide to allow them to end anyway. That's what Antonovsky researched and came to the Salutogenesis model: in spite of trauma, when we find/allow meaning and coherence, the blueprint of suffering doesn't attract us anymore. I think we humans have more of the capacity than animals do.

I'm thinking about [https://www.hellinger.com/en/family-constellation/|family constellations] being good for this. We experienced it on this year's convention where dear Anu led a constellation. There are many ways to do this as well. It has a relieving effect to the whole system in which the story runs.