Learn English – One word for “important matters”

I am looking for a single word to fit in a phrase such as

I sent him a letter about the important matters in my life.

or

I love to speak with my friend concerning important matters in our lives.

I am looking for something like an antonym to minutiae. The only one I found was generality, but that does not confer the idea of importance. Milestone is not a bad word, but it more denotes an important event on a timeline.

Is there any such word in English?