Schizophrenia....my friend has it and i need help!?

my friend has undifferentiated-type schizophrenia due to a brain tumor. hes changed alot over the past year, i dont know who he is anymore. he has around 30 people that live in his head. i have talked to a handful of them, and its weird talking to them, i feel bad about it...should i? at first it scared me, now its just like a regular thing. there names are shadow, sorrow, woe and slieth, they all have different personalitys. just today, they dont want me talking to their "master" domenick, they told me that i shouldnt suffer because of domenick. but he is, or at least was the one person i would confide in when i needed to talk to someone. should i just forget about him? its hard to say that since we were really close. all he does now is insult me, and laughs at me if im upset over something. im tired of him pushing me away. i know why hes like this, his last girlfriend left him, didnt say why, just left. now hes ruined in a sense. HELP! this isnt a joke, schizophrenia is confusing.