Right I know this girl like about 2 years but we only started texting properly like 2 months ago by text.. A few weeks after that she is with a guy.. Yet she is still texting me, a lot. I have told her that I like a girl but I can't do anything about it and she said tell the girl how you feel.. I really like the girl but I don't want to ruin a relationship or worse never be able to talk to her again because things are too weird between us. I get so annoyed about this every day, its tearing me apart. Maybe some of you think I'm a weirdo but I don't really care. If you have any advice please reply.

At this point, since she's already committed you have two options

1) Wait it out
2) Move on

But letting her know at this stage that you like her isn't a very good idea.