OP - ds is 15, and before Christmas in an argument he stepped over the line, much as your teen has done.
After lots of talking etc, we are back on track. I remember actually my middle brother doing a simliar thing at that age.
I think it is one of those moments when they go to far and have to rake back their self control. I don't expect it will happen again, bit my suggestion is that you take the adult role.
After his outburst, a lot else happened, and a I posted up thread, you were very out of order putting the marriage thing on him.
If this was me and ds, I would go into his room. He may say get out or I'm not talkign to you.
I would then say - well, I need to talk to you, and I need you to listen, you don;t have to reply, but you need to hear me out.
then apologise for the out burst, don't explain it away, just leave it as an apology. Also for the photo and the wedding thing.
The make it very clear that you love him and he is not responsible for the argument between you and dh. Also make it clear that you and dh are not about to split up.
Then leave.
When he comes to you, which he will, you can THEN say, we do need to talk about you throwing a knife at me and shoutign in my face don't we? At which point I am guessing he will admit he was out of order and apologise.
At the moment you have a stand off. The adult has to break it, on your terms.
This is a completely seperate issue to your dh.
(And can I just say, if you don't cook, there are 3 teens and another audlt in the house, and a chip shop down the road. You are not being a matyr. In fact, I in the long run, put the teens and dh on a cooking rota. once evryr 2 weeks per teen wouldn't be unreasonable)