Death and secrets in polyam

I need some outside perspective please. My partner is on hospice. She keeps her poly a secret from her family. The result of this is I have barely had contact with her and any contact I do have is snuck in when family gives her space.

We were going to get handfasted because neither of us wanted another legal marriage. I feel like that level of emotional commitment is incompatible with being kept a secret.

I feel like pushing her for this is screaming what about me while she's the one dying. I also feel heartbroken, like how do the last 4 years square with being shoved aside and only seen when convenient. It feels like I went from her partner to her acquaintance.

I'm being ripped apart by the fight inside my head and need some help. I know there's very valid reasons to stay in the closet. I'm hoping someone more experienced with being in the closet can help me with understanding how the 2 things (me being her secret and her calling me her partner) can be true at the same time.