There will be jealous moments, from both your kids.
I talk to mine about how they are feeling but I dont try "fix" their feelings, I tell them Im sorry they feel jealous and ask them if more cuddles would help. I try involving them as much as I can and making sure I still do the things I that I know are to each kid and heaps of cuddles.
We also involved them alot pre-birth, got them talking to my tummy saying good night etc.
Im sure it wont be as bad as what you fear