Frustration

I'm becoming so frustrated with my oldest son. He's 3 (4 in June) and is going through a phase that is so hard for me. He scratches, hits, pinches and will not listen to me. He seems angry a lot and I'm trying really hard to show him love and give him extra time, but all that seems to do is allow more time for him to hit me. He just asked me to do something and I said no and he pinched me really hard. So I grabbed his hand and slapped it hard because I'm so tired of getting beat up by him. I try putting him in the corner or sitting to have a time out, but he kicks at the wall and goes limp and struggles against me. It's wearing me down and I really hope this phase will end soon. This was nothing but a vent.