Personality changes with gbm???

Hey it's Kayla again!
I'm down to the point where there is no more protection and just wanting help.... Not only help but even someone with a similar situation.. My father was diagnosed with gbm stage four and was told it was inoperable .. Skip forward til now (7months later) and our last MRI was an enormous blessing saying his tumor has shrunk by 25%!!!! Huge difference!!! We were so pleased and it brought so much hope to myself and my family but not so much my father... He is very pessimistic about everything even though we found out this miracle but that is not even what I finally came back on this website to talk about. My father has become extremely aggressive and paranoid and is not only accusing my mother (his main caretaker and wife of 25 or more years (not sure exactly)) of infidelity and that's she is trying to kill him and everything in between and is still trying to drive and drink alcohol even though he was directed by doctors not too and plenty of other occasions where he has told me or my older brother never to come to our childhood house again or even been mean to my fourteen year old sister who still lives at home with my mom and dad.. He hides his pills and then forgets where he put them and then accuses my mother of taking them from him etc. the examples go on and on....I feel like everyone has just accepted the idea that this is who he is and this is just his way of dealing with the situation while I can't help but notice that he did not have these tendencies before his diagnosis and truly believe that this is not him talking and saying such terrible things when we are very loving and caring and honestly trying our hardest to make his life as good as possible and show him all of our love for him..........if anyone else has delt with this type of symptoms please help me and my family and let ,e know how u succeeded in dealing and with what methods... It's come to the point where I don't feel comfortable with my mother and my sister living with him and I know in my heart it is not his fault but at the same time unless we find a solution it is not healthy for either of them to be there.... Honestly I have noticed that not many people have talked about these symptoms or if they do its very vague because no one wants to talk about their suffering loved one or themselves in this way but I'm out of options and out of prospective solutions and I'm just looking for more people who are honest enough to admit that they can relate or help me find something or ease these symptoms or help with fixing them... Thank u so much!!!! All replies are greatly appreciated!!!!