I know when I was 19 I'd have wanted to know about my mom's health. (Some I'd unavoidably known about before that because she'd had operations and stuff, but a lot I didn't really understand until I was a teenager.) I think it kind of depends on the kid, but I don't think it's too young to be "burdened with" things like that.
I'm sorry about your son. I know when I was in my 20s, which is when I moved to the UK, I was pretty horrible about calling my parents too (though I don't think they made it easy, calling at one specific time every week no matter what, and almost never at other times, but I was still terrible). It didn't mean they weren't important to me, I was just no good at organizing my life at that point. I hope he does still think you're important, but it's understandable that you'd feel hurt, especially when you've got stress and worry about your health on top of that.
no subject
I'm sorry about your son. I know when I was in my 20s, which is when I moved to the UK, I was pretty horrible about calling my parents too (though I don't think they made it easy, calling at one specific time every week no matter what, and almost never at other times, but I was still terrible). It didn't mean they weren't important to me, I was just no good at organizing my life at that point. I hope he does still think you're important, but it's understandable that you'd feel hurt, especially when you've got stress and worry about your health on top of that.