Get him some help. A post-baby crash is a real thing.
Also you need to let him forge his own relationship. What are you doing? Criticizing? Withholding sex? Anything he might perceive as ‘punishment’ is not going help. I’m not attacking you, but you need to cast a wide net to solve this.
I became a father at 47. I was terrified. But our son is the best gift I’ve ever had, and I have faith that this can happen for your husband also.
You can get counseling at Focus on the Family. Dr. Dobson’s book On Raising Boys is wonderful.