When my mum was clearing out my grandmother’s house (I was very, very close to my grandmother), she found a card I had written to my gran about 20 years ago when I was still at primary school, my gran had been keeping it in her bedside table.
My mum was torn whether or not to tell me, given how upset I had been after her death/funeral etc.
She told me anyway, and while the thought of my gran keeping that card next to her for so long had me in floods of tears, it’s a final, clear image that I have in my head of my gran which I’m now glad I have.
I don’t remember with any great clarity the last time my gran told me that she loved me (despite the fact that she did it regularly), but finding that card was a lasting way for her to have done so.
It will have you in tears, but I would read the cards. It will be a lasting, good memory.