Sorry to hear this, sounds as if the situation is deteriorating rather than improving. These don’t sound like symptoms normally associated with a TBI, and since his TBI was six years ago it doesn’t seem likely to me that it’s directly related.

In any case, for your sake as well as his, he certainly needs psychiatric help. It does seem like he has some symptoms consistent with bipolar disorder. BPD can be concurrent with ADD, and there are some studies that suggest a genetic link.

I don’t know what the laws are in Kansas, but if his abusive behavior suggests he could be a danger to himself or others, you may be able to petition to have him involuntarily sent for a psychological observation and evaluation (this laws exists in Arizona, I would check the state mental/behavioral health department or a family law attorney to see what the laws are there).

Certainly sounds that he needs help, including therapy and/or medication. Since he is under 26 he should be eligible to be covered under your health insurances, or possibly Medicaid since he is unable to work.

Best to you all.