PhyllisA I am so sorry for your pain i didnt realize the extent of what you were goimg thru, expecially Mental illness. One thing that may help, it wont change matters but try to remember its not always his fault either. Its just a shame they cant help him with medication, because it may make a world of difference. But I understand you would not dare mention it to him. Do you take him to the family Dr, Maybe if you do, without him knowing talk to the Dr and let him know. Alot of times he could give him something to calm him down and he really wont even realize it.
Remember this is not your fault either mental ilness is horrible, its alot of guilt for everyone im sure.
The one thing to do and trust me this works, when you get depressed, angry or feel guilt remember its just the devil finding your weakness and feeding on it. My Dad told me this and i swear it works, when you feel you are ready to go over the edge say, IN THE NAME OF JESUS CHRIST SATAN GET AWAY FROM ME. My Dad said he will run because he is scared the death of God. Then say Jesus possess me over and over, You will feel a calm cool feeling. It really helps, My Dad said the devils weapon is fear, he knows our fears and uses them to hurt us.
He said when we get real stressed you know the devil is near, I hope this works for you. When I get crazy over anything in my life, money, kids, up comming events and see its really bothering me i know the devil is working overtime. SO when i ask Jesus to make him leave, my problems dont go away, but i feel instant relief of dealing with them, and they dont seem 1/10 as bad as they were a minute ago,
When i keep saying Jesus possess me over and over it makes me strong again. Then i think hey game on. Now I got Jesus to help me, he will take over now. And when you truely believe, its like, ( in my mind, okay I dont have to worry what to do or not to do, its vacation time in my mind, Jesus will take over the shift for the time being,) And you know you cant escape reality (unfortunately) but you cant fix the situation either. You can only deal with it, then when you really do have to deal with it, he is working thru you, and showing you the best way to do it.
So whenever the bad times come, and you know they will remember its the devil trying to get you away from God. My Mom always said he is always close to the good people because he doesnt need to be near the bad, hes already got them. he wants Gods people. As crazy as that sounds it does make sense. Just know hes after you because you are good, and he wants you away from God. So when you call Jesus its like putting out the flame. You will see also when you call on Jesus your anger is like that flame, it goes right out.
So please know what you feel, especially the guilt is so normal. You Feel guilty because you hate the way he treats your Mom and you hate him for that. and you hate yourself for feeling that, and You Love him so much at the same time. How could you not, he is your Dad.
Maybe when you are around him keep saying Jesus please enter him, please enter him. Jesus can humble anyone. Good Luck, you are in my prayers. Hope this works for you , its done wonders for me.