Say him: "My boyfrend has black belt in karate".

Well, just like anyone you'd meet online - give it time before you meet. If you're feeling unsure, just say it might not be possible to meet in this time. If the other person becomes upset or angry about that... well, there's your answer!

Hello my dear friend if you come....what can i posible every think will do...

Thanks a lot!

Unlike Chinese, in a question such as this one we use the Present Unreal Conditional. It is used to talk about what you would generally do in imaginary situations. “If one of your new friends on italki wants to come to your country to see you, what would you do ?”