Is it normal?!?!

Okay.. so.. i feel like a horrible mother right now... The closer it gets to me having my next son (within the next 12 weeks) in November, The more anxiety I have. I'm so scared my first born son isn't going to want anything to do with me or that he's going to feel left out. He's three. I'm scared I forgot how to care for a newborn. I'm scared of raising another baby. Don't get me wrong, I'm super happy and can't wait til he gets here. I'm not saying I'm not going to love him. I'm just soooo nervous about how it's all going to take place when he gets here.. please don't bash me.. I'm only human here, I suffer from anxiety as it is. I feel soooo shitty for feeling this way. A friend said she had sort of the same feelings but she says it goes away once the baby gets here.