I've been dating this girl for about a month now, and it was going really well and we were really liking each other. I was at the point where if I was to go out with my friends I wouldn't be getting with other girls. She said to me to come over and we need to talk, she then told me that she went out on the weekend and kissed another guy, soon after she said she went back to his place and they slept together. It hurts so much cause she said she does like me and she still wants to hang out. It goes against everything that I stand for to keep hanging out with her but there is a big part of me that really wants to.
You said "it got to a point where when I would go out with friends, I wouldn't pursue other girls." well, she didn't pursue other guys, but it happened and she got with him. Very mature of her to tell you. You never said "we decided we liked each other, and didn't want to see other people; we became exclusive" therefore, your behaviour is appropriate, and her behaviour is appropriate. Your emotions are valid, but only her reaction is valid. She wanted to sleep with him, so she did, and she told you. You are hurt by it because you like her, so you tell her so, and express that you would like to be exclusive. No one cheated.