“he used to work til 10pm ish every night then would go for work drinks thurs or fri then out on sat too (tbf i would often come out too when i was younger) in bed the rest of the time”
Right. So he started out drinking too much and being a bit shit as a partner and he has carried on even though he is now a Dad.
You have to decide what your red line is, OP. Do you want to / are you willing to live like this until the children are semi-independent?
Think through your options and what you want from him. Once the new baby is of a certain age can you go back to work? Never mind the childcare cost, if he is a good earner it is there to enable him as well as you to work and earn.
Working gives you a level of independence and if you worked weekends, for example, he would have to pick up his parenting.
If you tell him your marriage is in the line would he attend couples counselling? Do that you can discuss in a safe environment how marriage and parenthood makes you feel, what you both want out of it and how his behaviour leaves you feeling?
Can you get him to agree to a basic level of quality family time, and for him to give you some time off?
Is he at all receptive and empathetic to your needs?
And Pp: ease off on the cool wives jibes; the full picture hadn’t emerged, and anyway this is the emotionally Neanderthal arena of AIBU. What do you expect? Nuanced sensitivity to the OP?