Need help on card writting
 

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It was nice knowing you, and hope you do well in Toronto.. We will miss you and please come and visit us when you have time.. I know i was really crazy and annoying!! lol... BUT I WILL REALLY MISS YOU

In this situation, it is more natural to call your friend by his/ her first name, so in the letter I will assume that your friend is a boy called 健二

健二に出会ってよかった。トロントにもお元気に。健二 のことは忘れないよ。暇があればまた来てね。いつもご 面倒をおかけしてすみませんが、決して忘れないよ、健 二のこと。

I'm not convinced that you speak Japanese. No natural balance is to be found among some of the phrases and sentence-enders used.

訂正して頂ければと思います。宜しくお願いします。

how should i write it?

This is my attempt along your translation.
健二に出会ってよかった。トロントでも元気でね。健二 のことは忘れないよ。暇があればまた来てね。いつも騒々しくしてゴメンね(笑)。本当に寂しくなるよ。
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To the OP, I think it would be better to write in your first language, and add simple phrase in Japanese at the end of your message with your signature.

色々ありがとう、元気でね。(Thank you for a lot of things, All the best.), your signature.
元気で！ また会えるといいね。(All the best to you, I am looking forward to seeing you again.), your signature.

Or, if you had ever learnt Japanese,
Your own attempt in Japanese without anyone's correction first, and your original message in your language.
Sorry for my poor English.

ご訂正してくれてありがとうございます。勉強になりま す。