Unfortunately, in the second link you sent me, I can’t access for some reason
[...]
Which is weird, because when I had the jetpack, I had to connect the blog with the italianeography account in order to view the stats, otherwise it didn’t work.
That link can only be accessed if you're logged in to the WordPress.com account you originally used to connect Jetpack to WordPress.com.
If you're logged in with another account, you won't be able to access that page.
To make sure you're logged in with the right account, check this page:
http://wordpress.com/my-blogs/
You should see your Jetpack site there.
I’m only concerned if there are people that follow some article conversation, and they won’t receive updates anymore.
Since you've deactivated the Jetpack plugin, they will indeed stop receiving notifications from your site.