Not happy

Krista
My husband can be verbally/emotionally abusive. He admits to saying things that hurt on purpose. He does apologize if I tell him what he's doing. But he hasn't changed his behavior. 
He breaks things when he is mad and thinks it's not a big deal. 
He drives 20 MPH over the speed limit and cuts people off even with our son in the car. When I ask him to slow down he says my job is to watch the baby and not how he's driving. I'm terrified to let him drive alone with the baby in the car. 
He's been helping a bit more with our 4 month old but is now acting like he's so exhausted. 
Sometimes it seems like him unwinding (smoking pot) is more important than anything. 
I felt like I wasn't even honored on my very first Mother's Day. My gift was a joint birthday and Mother's Day gift he had me pick out myself (well he said he wanted to buy me new sunglasses and I picked them out). Not that it's about the gift but there was nothing special about the day. He didn't try. 
I take care of our son AND work from home. We hired a nanny part time (all we can afford) but she either made a bogus excuse to not start today (her first day) or she really did have to have surgery. Never mind she said she accepted a background check but upon investigating today it wasn't completed. Now I'm scrambling for help. 
I live across the country from my entire family, moved out here for my husband's job. There are way too many people and I don't like it here. I miss home. I don't know anyone here and I have no idea how to relate to surfers and fake blonde pop-culture princesses. 
I've tried talking with my husband and he's always apologetic but nothing changes. He refuses to get help or to go to a doctor. Like flat out won't talk about it. He reluctantly says we could move back to my home state and that he would "mow lawns even though I spent 7 years on my PhD." His way of saying he doesn't want to. 
I feel like the only one I have is my 4 month old son, who I desperately need to protect and I have no idea how to do this. I can't have him hurt, I can't have him thinking it's okay to behave like his dad. But how do I get out of this situation with nobody here to help me? If my husband won't help himself, I just can't keep doing this anymore. 😔