1) He (and you) need to go to parenting classes, already. And, maternity classes, which hospitals offer to couples before their baby is born. It teaches basic care taking of a baby etc. Did you and he sign up for classes like this?
AND if your Boyfriend refuses to attend these important classes... then, this will be a "window" into his level of maturity and character... and it will show you, what kind of guy he is or not. And if that is good enough for you. Love, is not everything. Because, Once a baby comes into the picture, it is also about how mature and grown-up your Boyfriend can be, about being a "parent" himself. Or not.
2) Do not marry him... if he is like this. Because, this is only the beginning of baby nerves. Once a baby IS born AND comes home... the stress... INCREASES.
3) You DO, need to tell him things and be able to talk to him about things, no matter what it is. Because, you will both be parents. Soon. And if you both cannot settle things like this... then it won't get better once a baby is born.
4) Your Boyfriend is not a child. He is an adult. There is no "should I let him do it to relax himself until we have the baby..." Because, you are pregnant NOW and you BOTH have to plan for the baby, and both be a part of it. And if he cannot handle it now... he won't be able to handle it later, once a real baby is at home.
5) He is only a Boyfriend. And YOU need to: decide, if the baby is going to have your last name or his on the birth certificate.
You have to do research, and see what types of "custody" there is in your State. There are MANY different types of "child custody." So head's up.
You need to also research what the custody laws are in your State, between unmarried couples.
6) If you are having issues, about him drinking, and this is how he handles "stress" and he gets all defensive when you asked him about it just once.... then, these problems, will most likely increase, once the baby is born.
7) At least his friend is with him, and drives him home. But gee... what if one day or night, your Boyfriend IS driving the car.... and/or has the baby in the car too, and he is just not thinking?
8) Do not make excuses for him, and that this is just about him being stressed because this is his first baby etc. You both need to talk about it. You need to tell him it is problematic. You need to realize you cannot make... a guy do what you think, and it is not about you "letting him" or not, behave that way. He should be cognizant enough on his own, to control himself.
9) Any problems you both have now, will not go away after baby is born. And many more problems WILL come up.
So, you have to decide, on your own, if this man is good enough to be a parent. You will be a Mom, and he will need to be there for you and the baby, too.
10) things get, very complicated, and very stressful, once a baby is born.