Is there somewhere that I can learn to grow some hair on my chest, to be strong enough to say No and mean it.
Welcome, MeMa. You've arrived at the right place. almost all of us have been in shoes similar to yours.
I don't need to tell you that you have a few things weighing down those shoes: one is that he is under 18; you still have legal responsibility; two, you still want things for him--that he may not yet want for himself; three, there is a triangle involved, in the name of his Mom, where you can be potentially undermined; four, you don't want him to be hurt--thus you are set up to take consequences onto yourself, rather than see that he receive the natural consequences for his behaviors.
All of these factors disempower you. The same with the rest of us. As I said, we have been through it too.
I think you will find help and support here, but it's not an easy road. I have a couple of questions. I would have thought that there would have been some hesitation to return him to your house, given he attacked his younger brother. This is an issue of potential child endangerment of the younger boy. Was there concern by the authorities about this? How long did the psychiatric hospitalization last? What were the findings? What's going on in school? Is he in school, now given the pandemic?
You are right all of these things shouldn't be happening:
He threw his brother's Playstation on the cement, smashing it. Police were called and he had his first psychiatric hospitalization. He makes demands of me continuously. Will not take No for an answer. If I am in bed, and he wants something, he will bang on the walls, call the phone, pound on the doors until I give in. I have had to hide the knives, my purse and anything that he could use of mine.
This is not true:
I am not strong enough to stand up to him.
I can understand this, but this position may undermine you if it means you hold back with taking a stand:
I don't want to get the courts involved.
You deserve safety in your home, for yourself for your other son, for your pets and for your things. This is non-negotiable. It does not help your son that he runs around like a hulk with everybody afraid of what he will do.
He doesn't seem to care that he hurts me.
But you have to care if he hurts you. You are the one right now that knows the limits and must find a way to enforce them.
I don't want him to end up in prison
You can't stop him from going to prison. There is nothing at all within your power or mine to protect our sons if they are hellbent on behaving badly or can't control their behavior. The single best way in my mind to avert this outcome is to set strong limits, now and consistently reinforce them. It's hard. But doable.
Damage to your home, injury to you, to your family, to your pets, are crimes. I think what every mother here would tell you is to call the police every single time he threatens this let alone does it. He needs the consequences. Whatever they may be. You are doing the right thing securing what you can. When he stalks you in your house, when he bangs on walls, etc. given his already demonstrated propensity to violence, these actions portend more violent acts. I would call the police every single time.
If he has already hurt you or the animals repeatedly the best thing that can happen now is if he gets a probation officer so that you have back up. It sounds like this incident with his brother was not the only time. The outcome that you fear is already here.
It may have to be faced that your own and your custody are not the places for him to be. How soon will he turn 18?
We as parents have all had to face the reality of our situations and the reality of our children's behavior. Our love, responsibility, hopes, and fears are not determinative when gone off the rails. Our children are driving this situation, and in my experience, they cannot be stopped, until if and when they decide to change or they are stopped in one way or another. It is very hard for even two parents together to stop a near-adult child when he is on the rampage. But you are strong enough to face the reality of your situation and to take steps to protect your home, your family, and yourself.