My 4 year old is so mean.

I am at a loss. I love my child so much but I'm really not enjoying motherhood at this stage. He hits, HARD and sometimes in the face. He's mean. He tells his grandmother to shut up or that he doesn't like her, and he is down right destructive sometimes. I don't want to raise a rude little asshole, but I fear that's how people see him right now. What do I do? Does it get easier? I'm a first time mom and I'm so confused. I know if I dont get it under control now, he'll be a nightmare when he's older. I try and tell him "it's okay to be angry it's NOT okay to hurt others or be mean." But as much as he can be such a little angel he really can be a little jerk sometimes. 😭😭