Falling apart.. and don't know what to do...

I'm 15, and i met this guy on-line... like 3 years ago...we became really close... I think I'm falling for him.. like falling...

I know I'm young bu when I talk to him all my problems just disappear..! that has to be a good thing right?

The only thing about him is that he's... 18... and he'll be 19 soon...

I don't know what to do!!

Right now I'm dating him... we love each other... should age really matter? Like my grandpa and grandma were 20 years apart....

Am i doing the wrong thing..?

Pease help me...? Let me know.. what to do.. please?