Hi. Welcome to beyond blue.
In my reply I want you to know that I and many of the other users here are not professional counselors. We are just people like you or your husband.
You asked whether this sounds like depression. It could be. It could also be a stressful period. It could also be anxiety or combination thereof. My initial thought was for you to talk to your husband about this, but it seems that you have already tried that. With that said some other ideas for the conversation can be found here...
On him not talking... I still struggle talking to me wife about my issues, because I have all these thoughts running around in my head, that I don't know where to start. And not wanting it come out all crazy like, or disjointed. Sort of like a Billy Connolly concert gone bad. But I can write these thoughts down in a email and send it to her. So I am wondering whether his inability to talk to you is related to that.
From your perspective, which phase do think your husband is in - Unaware, Denial, Resistance, Starts and Stops, or Acceptance? Depending on where he is, different conversations can be had.
Lastly, if he is suicidal, then professional help should be looked into. And he would/should also find a list of reasons to live and have a safety plan. Mine live on my phone along with other distraction and coping tools.
I know this is a tough period for you (both), but also try to be patient, with yourself and your husband.