OP I'm going to let you in to a little secret, which in hindsight is quite comical. Obviously it wasn't at the time!!
When I was in the very early stages of pregnancy with DC1, I kept having nightmares and day-time panics about the baby coming out the 'wrong' colour. In my head I was thinking about the stories you hear of genetic 'throw backs' to a long-forgotten ancestor of different ethnicity meaning two white parents give birth to a black baby.
Anyway, I was convinced that this was entirely possible and likely and although I would, obviously, love my baby entirely and completely, what would other people say! No one would believe me that the baby belonged to DH!
I confided in DH one day really wanting him to say something along the lines of "if we have a black baby, I'll know it's mine and we'll love him/her all the same and everyone else can get f*cked". But, instead, he looked mortified/confused/shocked and asked me if I was trying to tell him something. At which point I burst in to inconsolable tears. This was in Waitrose!!
Oh... and then there was the middle of the night breakdown following the nightmare about having triplets. I believe my exact words to DH were "twins I can almost get my head round. But triplets... what the hell am I supposed to do with triplets... I've only got two boobs!!!"
I realise your feelings are more serious than this. And you need to get to that MW ASAP - when's your appointment? Can you get one sooner? But my point is... you must hang in there. This will pass - you might need help, but it will pass.
Have you told DH how you're feeling yet?