Is it normal to feel emotionally vulnerable?

In a way that I cannot keep a brave face on the whole time. I try hard to mask emotions through humour but I feel like people still find ways to push through that and inflict pain on me. I wish I could train my emotional response where nothing can catch me off guard. I'm sick of being affected by people's bs when they themselves do not give a damn about what they're doing to others. I know this is vague but in general have you ever felt like you're not emotionally rigid and that caring about things/people make you vulnerable? That actually being kind, you become an open target for the bullies in life? Is it normal to think that to close vulnerabilities you, yourself have to become a bully? I hope not.