Should I give her a second chance?

She cheated me with this. He sent me all their mails and it seems that what he said was true. He also claimed that they were physically intimate. He told me the way she kisses and marks on her body. When I confronted her she admitted to chatting with him but she denies any physical relation with him. She said she is feeling bad that I had lost my trust on her and cried when saying that. I knew she chatted with him earlier (I caught her chatting twice) and we had big fights on that. She said that she would never do that again and was feeling very guilty but she did it...Should I trust her now that she wouldn't do it again? Though she denies getting physical I doubt how he was able to tell the marks and tell the way she kisses?

I love her...I cant bear if she is feeling bad...I want to trust her..But again I have all these questions that make me hate her...I start my day hating her but end u missing her by night. What should I do? My heart wants to trust her but my mind doesnt agree..How can I trust her comletely?..If I leave her will I ever be able to love anyone else like that? I'm not able to do anything or concentrate on anything..All I do is think about her all day...Should I admit it as my fate and forgive her and give her a second chance? Will I be able to forget all she had done and be hay with her?

She is my first love and gf for 6 years. We are in a long distance relation since 2 1/2 years...