My ex-boyfriend doesn't want to leave me alone, I'm involve with someone whom I've known for almost six years now but our relationship started to be serious in 2011, the person I'm involve with is my boss, I love him so much that I even moved in with him, he's not married, he was never married and he has two kids I have one... the problem with my ex is that he's threatening to kill me, and take my boss to court for being in a relationship with me and I don't love my ex anymore we've been together for 4 yrs.

Keep the evidence and get the cops involved. At least make a complaint.

Like Tal said, you have to get the cops involved. Keep all evidence of his threats to you, get a restraining order, whenever he contacts you hang up. Take any of his threats to the police.

Get a new number, delete your Facebook.

You have to be proactive about this.

I don't know what he thinks he'll win in court. You have every right to date whomever you want if you're both of legal age to date.

Call the cops, setup a restraining order, and make sure that you are in a safe place. He is just desperate, not to mention psycho. Threatening to kill you is A LOT worse than you being in a romantic relationship that you shouldn't be. Above all, remain calm.

You will need evidence he is saying this ( and take the threats serious) there are killings every day in the US where one partner did not want to lose the other.
Report the threats, ( it is against the law to even threaten to kill someone)

Next why would he sue or how, is there company rules on dating a fellow employee or dating someone you work for ?
It is a bad thing to do, can cause a lot of hate and issues at work, So I would advise changing jobs or changing departments and not working for the man you are living with