Hes pissing me off.

My SO is 28 his brother is 21. He constantly continues to hang out with him to drink and smoke like he doesnt have a family at home leaving me pregnant and dealing with our 3 (4 next month) old child by myself. I'm tired I'm frustrated. I just want to cry. It's always been an issue. He doesnt see anything wrong and gets upset when I ask him where he is, when is he coming home, or what hes doing. I'm just so tired of it. We planned this 2nd child and here I am stressed constantly and telling him means nothing. I feel like just leaving sometimes but I know my daughter loves him and I just wished he would care or pay more attention to us. I'm scared this will continue when baby # 2 is born and idk if I can handle that. I just had to vent sorry for ranting.