Awww, no fair
I'm sorry that you are going through the chemo AND your new baby bonding more with your hubby.
We got Luna after our Starr died and she immediately chose my husband as her favorite. She will still hang out with me if he's not here, but when he's home, I don't exist. We got Izzy a couple of months later and I thought OKAY this one will be MINE. Uh, nope LOL she loves Daddy more than me too.
I feel for you. Getting another dog might work, might not. There's no guarantee on who they will bond with more strongly. Hope someone that knows more than me will come along with some good advice, but in the meantime my only suggestions is to take over the majority of his care and training and maybe just maybe that would help.