Husband hates job and depressed

When my husband and I met, we were both college students (I'm 26. I started college after working for a while to save money and deciding what I really wanted to do). He was about to graduate and I had another year. We dated for a while and talked about getting engaged. We knew we both really loved each other and loved what we brought each other in the relationship. However, during his last semester, I ended up pregnant. We were both terrified, but he told me he would be there for everything and that he would support whatever decision I made. He graduated and started looking for jobs while I finished up the semester and decided to take some leave, as the pregnancy was difficult and my morning sickness never went away. We decided to do a courthouse wedding with the intention of having a big celebration later so we could all be on his work insurance.

Now, our daughter is 4 months old, he is a teacher in my small hometown, and I am a SAHM. Everything was great for a while, just the usual new parent/newly married struggles, nothing we couldn't get through. But now, he comes home frustrated and angry every day. He hates where we live, the people he works with, the students, and his life in general. He is overworked and overtired but won't take a personal day. He hardly eats, doesn't sleep, and doesn't spend any time with me or our baby. He is at school working 7 days a week (they need to hire another person in the program, but that's another story). The other day he was angry and tired and told me getting married was a mistake and that he didn't want to be a dad. I asked him if he still loved me and he said he did. Sometimes he loves being with our baby, other times he wants nothing to do with her, or me. Last night, he came home from school really upset, threw over a chair and went out drinking. I was so worried I contacted one of his coworkers who is aware of his struggle and his best friend. They both called him and tried to calm him down. He eventually came home, but he picked up cigarettes on the way (he's never smoked in his life) and smoked a good portion of a pack. He told me that if his life insurance was in line yet that he would have ran his car off the road a long time ago.

I'm crushed and feel defeated and don't know what to do. We've only been married for 3 months but I already feel like we're falling apart. I love him dearly and married him for a reason. Our daughter is my world right now, and I think he feels isolated and feels like we didn't get to enjoy the process of getting married and having a baby like we should have. But I told him that he's all I want in the end, but it didn't help. I want our daughter to have a happy life, and I would be lying if I said I haven't thought about telling him that if he doesn't get help, I'm leaving. I don't want to, but if that is the only way for him to get help, I don't know what else to do. I made him an appointment with our GP to see about getting something to help him sleep, but he skipped. I guess I am just at a complete loss. I support him no matter what, and if that means getting a different job and moving away from my family, I would do it. But getting through this part is terrible. And I'm worried that teaching at another school will have a lot of the same challenges and it will start all over again. I guess this post is to vent and to know I'm not alone.