Stoke recover I need your advise!!!!?

My brother 32 had a stroke two years ago. He is very smart, is able to walk and teaches sales cl at the local collage. For the first year he was very humble and happy to be alive. Senses Augusta he has been become mean. At first it was to distant friend, then close ones, and now to my parent, his wife, and espchely me. We use to talk every day now I can go a week without talking with him and the only way is if I call him. If I do call him within the first few moments he will say something nasty and really to not talk with him for a another week. I don’t know how to deal with him. He is very nasty we use to be close and support each other. Last night I went over to his house and he hardy spoke to me but carried on a conversation with my friend that I brought. How can I help this, what can I do to change thing? Please any advise would be great!!!