PPD in my husband?

My husband and I have an eight-month-old baby and I'm seriously thinking he may be experiencing some form of post-partum depression. Our daughter's birth was a bit on the traumatic side, and she was born with some issues that, while not life-threatening, did require surgical intervention. I wound up having to leave my job to care for her full time. That puts my husband in the position of being the sole breadwinner, in addition to going to school for his degree and being a first-time dad.

In the face if his new situation, he's shutting down and shutting everyone out, including me. He ticks off daily tasks in robotic fashion. If I ask how he is, his answer is, "I'm here." He's completely ignoring any and all attempts from his friends to even say hello, much less talk. He's irritable and terse, and when we find out about friends or family who are expecting, his responses are snarky quips like, "Give them my condolences."

He's a lot better with our daughter than he was in the beginning. The only time I've seen him laugh in months has been at her antics. I honestly can't remember the last time he's really smiled at me, though. We've always been a close and affectionate couple, and I want that back!

How can I help him? Or can I? He flat-out refuses to go to therapy or take any kind of meds.