How can I deal with my taken crush?

Please Help me...
There's This lad I know, I only know him through the net...
and I really like him. I've told him and everything he said he likes me to
but he has a girlfriend...
But I don't think he likes her...
I Ask him if he loves me why is he still with her..
and he said..Because I've known her for 7 months and don't want to hurt her feelings..
And he says he wants to keep his conscience clear...[But he talks really dirty to me ;l]
and aloud of shiit..
and when I went back to school, I Ended up crying in science I wrote my feelings down on a piece of paper
and the teacher took it and thats when I began to cry...
When I got home I was really upset.. and my mum & dad wanted to know so I told them,
And I Get really Jealous when he Talks to other people and laughs
Am Really confused...I keep feeling like I want to kill my self...
Lately about 2 months ago I haven't cut my self..and now I've started doing it again..
he knows how I feel..
I just don;t know what to do I try and forget about him, but it just doesn't happen..
Please help I feel really depressed and upset all the time...
His ex was my best mate... and they fell out and they made up as mates again and am proper jealous in case he becomes to like her again...his ex knows I really like him...but she don't like him his ex likes someone called sam

Find a guy that goes to school with you... you have to be able to be around him to make it work, or at least meet him... but he has a girlfriend and he says he wont break up with her... so you know what you have to do... forget about him... you can find better.

Hes just messin with you. Why is he talking dirty to you when he has a girlfriend? Doesnt sound like a trustworthy kind of guy! BLOCK HIM..Just stop talking to him all together!!