the old saying is "if it looks like a duck, quacks like a duck. Then it more than likely is a duck" comes to mind, it sounds a lot like the behaviour of an abused young man.
But the problem you have is, what do you do about it?
That's the hard part, and the truth is you just have to make your own judgements.
If you ask him outright he might run a mile and never be seen again, it might trigger a crisis, or it might be the chance he's been waiting for to finally talk about it.
I'm not a betting man, and there's probably other reactions I haven't mentioned as well, so you can see the kind of problems you might be faced with.
Depression can be caused by many things, so maybe a good doctor could recommend something, or better still a good therapist. Probably hard to find in N.B though, so take a look at your Gov't web site, there's so much good stuff on there for survivors and partners, the Canadian gov't really have done a good job http://www.phac-aspc.gc.ca/ncfv-cnivf/familyviolence/
That's a link to the 'Family Violence' pages, the CSA stuff is amongst it somewhere.
Whatever happens, you have to work with him and not try and do the work for him.