Its treathening consider verbal abuse?

My ex said that.

I saw a lawyer. I had it all set up. I kept a diary of all of his threats. I kept all of his voice mail messages where he made derogatory comments. I rented an apartment. Then I had divorce papers and custody papers drawn up. He went to work, and I moved out, taking only the necessary items for myself and my son.

He is trying to control you. Please don't let him do that to you.

Yes, it can be abuse, but not much done about that verbal threat legally to my knowledge. You tell him if he tries to take your child away you will call the police and don't ever leave the house without your son or I believe he can claim abandonment. You might consider seeking the help of an attorney if you are planning to leave and you think he is going to try to interfere and take your child.

What type of threat are we talking about here? If for example your husband is saying things like "if you try to leave me I'll kill you" you need to call the police and get a restraining order. And yes I'd also consider that emotional abuse.

Depends on if the person receiving the threat has a reasonable belief that it might be carried out.

Yes.

depends on what the threat is....

yes

That is emotional abuse. Make a plan, then get out.

All kinds of threats I can think of, in any context or any kind of relationship, are attempts to control another person. Whether it's parent-child, children (siblings or peers), or adults, the strategy is to use force & leverage to get a desired result or prevent something. It's often in response to feeling threatened or attacked, or even just vulnerable (afraid you might leave.)
The impulse to control another person is intimately related to fear, powerlessness & helplessness. This fearful/defensive root is common to all abuse!
Abuse happens on a continuum. In the largest sense, it's determined by its effect on a person, not by conforming to a legal definition. There are many kinds of behaviors & interactions that hurt or harm, because they're far enough along on that continuum not to be "optimal" or "nurturing," but they're not anywhere in the realm of being illegal, reportable, or prosecutable offenses.
Wishing you well!