Oh, Robin 
How old is your DS1? I've just had a second DS (he's 10 weeks old on Wednesday) and DS1 has taken to him beautifully - he's really affectionate with him. DS1 is two on Monday, and loads of people have looked at me disbelievingly when they ask and I tell them that there's no jealousy - seems they just want tales of scratching, biting toddlers!
You will lose the weight because you don't sit down as much with a toddler and a baby. I kept my baby weight with DS1, but have pretty much lost it all again with DS2.
It is hard work and it's overwhelming at times, but the good stuff is worth it, IME. I love that DS1 is a big brother and that DS2 has DS1 as a big brother!
Can you talk to your parents or is it irretrievable?
What do you need to do before DS2 comes along? Make a list and prioritise - I did this and it really helped. We live in a DIY paradise, but finishing the bathroom really helped, for instance. Well, almost finishing!
Work...well, you won't be there long, you'll be with your gorgeous boys.
As for worrying about dying - I think it's natural to be super-anxious about things like this when you're bringing a new life into the world and you're already responsible for a little one - but if it's overwhelming you, go and see your GP - antenatal depression is recognised and common and nothing to be ashamed of.
Chin up - you're not being ridiculous, you're being human 