Crush was my half brother? (please help me understand what this means)

Date: 9/17/2016

I was at this party and the three guys I like from school where there. I was talking to one of them ( Caleb) and he seemed upset. I asked him what was wrong and he asked me if I really wanted to know because it included me. I said yes. He showed me screenshots of messages between him and one of our former teacher. Turn out that he was our father but we came from different mothers and were given up to separate families. He started crying. My hand was on the table next to his and he held it. He was running his thumb over my hand in circles. He kissed me then pushed me away. He didn't want anything to do with me. My eyes got watery and I ran outside to the yard. I fell to my knees and started crying. My other crush Sam yelled that he was going to help me. I was crying so hard o couldn't see. He ran towards me but never reached me. No one but Caleb could. I loved him...