Feel like I'm gonna lose my relationship with my first child

I know it's just change and a lot of hormones. However, I can't fight the feeling that I'm losing something and not gaining something with the new baby. I want to expand our family and can't wait to meet our new addition but feel like I'm losing my first son. I know he isn't going anywhere and that having the baby will be our new normal but it doesn't stop me from crying every time I think that 'oh this could be the last night I cuddle with him before bed before I'm also worrying about the baby'. Am I the only one who feels like this with the second baby due any day?!? Or that my first son will resent me when I'm not solely his.