((((Catch)))))) Has he given you detailed plans for any vengeance on his boss? soemtimes men who are depressed channel the negative feelings into anger and act out rather than turn it inward that way women do.
You mentioned that you have also had depressive problems. Do you see a therapist? If so, this would be an improtant thing to bring up to him or her. I don't know what state you are in, but in some cases therapists have to report information they get if there is a clear and present danger to a third (or fourth) party. At the very least, you would get some information closer to the source than me.
If you don't have a therapist right now, it might be a good Idea to get in touch with one. This is a horribly upsetting time for you as well, and it would be good to get some support IRL.
Finally, if push comes to shove, you might want to call 1) a suicide hotline (some of the same aggressive impulses in what your son is doing are also present duing suicidal periods for some people) might have measures you can take in your situation, 2) see if you can't get your son to an emergency room 3) if you cannot do this call the police.
I'm sorry I can't do more, but I'm sure there are others here who have better information than I do. I wish you well,dear, and please, get help, you should not be trying to deal with this alone. HUGGGS