We have an adopted daughter, age 30.
Diagnosed very young as Bipolar.
Prior to medications, she had violent tendencies and was extremely erratic.
Today, she is moody and erratic at times.
Better, but still not a really good situation.
She does a tad better when in therapy, but she refuses to go.
If you feel your adult child is a danger to you, make sure Security is a top concern. Locks and alarms for your home. Call the police if he hurts or threatens you.
If you do communicate well with your child, you might offer to pay for a psychological evaluation (always pay the doctor directly) and offer him therapy as well. He likely needs medications.
Consider groups like Family Anonymous for yourself for Local Support or even short term therapy for yourself if you aren’t doing that already.
Having a child like this is very draining.