GF Problems

Ok i am trying to explain this but it is very hard so bear with me.

I have been with my gf for almost two years, very serious, loved each other very much i spose. Ok we had a few arguments but we had been through so much together.

When we started year 11 we have had more to do both studying after school not seeing each other as much. And i knew i was being off with her on purpose becuase she wa siwth me. But i felt she was being much more serious so i asked her if she wanted to go on a break and she said yes fine we didnt talk as much.

I find out yesterday that she doesnt wnat to get back together she doesnt feel that way anymore and that she fancied sum1 else? only a little bit but she has told him and been getting close with him, not too far though, but she said she doesnt wnat to go out with him! And now i am forced to get over her.

This isnt like her im not sure what is going on why would she tell him with no intention of anything serious?

Any thoughts please