It is hard when someone is abusing your parents no matter the cause. Moving out will probably make him worse temporarily, but in the long run may empower him. If he is violent when bipolar than he shouldn't be in your parent's house. It is a very real possibility that he may hurt them while in episode. Especially if he has already shown that he will push them.
You may want to contact your local Mental Health Association or NAMBI. they may be able to connect you with a support group. If he will go take him, if not go by yourself and share what is happening. They may have ideas you haven't thought of yet.
Supported housing (a monthly visit from a social worker and some supervision), supportive housing (more intense supervision and a daily visit from a social worker) a community residence (sometimes know as a group home) generally are under the same source of mental health funding and do take a part (a third) of a person's income (I am not sure if this varies from state to state this is true of the state I am in) but the income can include SSI (Supplemental Security Income) but it is true to be accepted for that a person has to be under a psychiatrist's care and following up with treatment but psychiatrist's can work with a person to help them understand why they need treatment. Also in community mental health living arrangements if medication monitoring is needed a psychiatrist can note that down and that will be followed up on.
He will probably be no better or worse living outside your parents home as long as he refuses meds and therapy. A supervised living situation like a group home would but they cost money, just as an apartment will cost money. He won't be able to get on assistance unless he is shown to have a disability and you need treatment for that.. to get a medical history of a disability. There is no easy solution if money is a problem.
Thank you all for your valuable advice. My only fear is that him living by himself might make his condition worse. Is this a possibility? How likely is it?
Thanks again.
What about assisted living for people with mental health issues, there are communality homes that are full staffed, were people can live for lengthy time? Might be something to look into if you think its a good idea.
If you fear for their safety, definitely something has to be done. Can you live with being the "bad guy"? Do you have any other siblings? It also depends on the state you live in. Here in AZ, to have someone go to a forced treatment center, they have to proven to be at risk by a behavioral health court. If there is a similar situation in your state, you have to consider it. If he is so oppositional that he won't take medicine or treatment, I doubt that he's going to move out willingly. But your parents would have to be the one's taking the initiative in a legal matter like that. parents are very reluctant to do that to their children. it's like a spouse that is being abused continually protecting the abuser.
You could talk to him and try to get him to agree to it, but they would have to support you and understand in advance that if your intervention didn't work, they would have to take it to the next level. Otherwise why even start the ball rolling?
As far as him holding an opinion of you as the "bad guy", maybe once on meds regularly he would be less likely to hold you responsible.
Rogelio
It depends on him, and any actions he chooses to involve himself in following being asked/made to move out would be on him, not you or your parents. Just let him know you all will always be there for him, but that you feel it is best for all parties involved. Being bipolar is no excuse to abuse another human being in such a way as yelling at them or pushing them, and your parents should not be obligated to have him in their home unless it is something they want.
The question, however, also should be: can he realistically make it? Is he working and making enough money/are the funds present for him to acquire his basic needs (shelter, food, and clothing)? If his bipolar disorder is such that he can't work, he should look into SSI, though he will need to have medical proof of having the disorder and it could take a while to be instated. If his bipolar disorder isn't that bad, then he needs to look for a job so he can meet his needs, if he doesn't already have one that allows him to do so.
It would likely be best if your parents ask him to move out, however, because otherwise you make yourself out to be the bad guy and he won't be as likely to listen because it didn't come from the people who own the house he is living in, the people with the real authority. However you do it, be sensitive to his needs, be sure to offer support (emotional, I'm thinking, maybe a little help finding a place and getting moved in), and don't point fingers. "It's because you treat them this way," would not be good. It's going to make him feel like he's under attack.
Best of luck!