M.C.
My children were 17 month apart.
When I came home I begged my husband to quit his job , to not ever leave me alone,:)
I was terrified to take care of two.I just got the routine down on one.
But all I can say is,it's going to be hard for a while, but you will come down with a new routine eventually, and look back, that it wasn't as bad as you thought.
Your first child will, soon be entertaining the new baby and they will have a good time.
I did my chores at night, I loved the quiet.
My second baby slept through the night at age 4 weeks.
I was so lucky, my first one was a terrorist baby.He never ever slept.
Surrender to some change, it will get nice and "normal" again.That is all I can say.
Good luck with everything.