I am sorry it came to this. I hope that this is the bottom your son needs to hit and that he will drastically change his ways. Don't be afraid or ashamed to get a restraining order and to insist it be enforced when he is released.
As for the boss, unless it is a very small company, you are entitled to FMLA leave if needed. You would need a doctor to fill out some forms, but it should cover leave for stress related medical problems for you or others in your family. Look into Family Medical Leave Act to see the specifics as to what it allows, what is needed to qualify and which employers it does and does not cover.
Please see a counselor to help you work through the feelings that this brings out. Domestic violence centers will be able to help at no cost to you. It is still domestic violence if it is a child abusing a parent. For me it was the best place to find help that understood the complicated emotions that come from being the victim of abuse by your much loved child.
((((((((((hugs))))))))))