’’私の友達が来月からシアトルに行きます。もう少しで彼と会えなくなるので、今日はその友達と遊ぶためあなたと遊ぶことはできません。’’

と友達に言いたかったのですが、うまく伝わらなかったのですがどういうふうに言えば伝わるか教えて下さい？？

I cannot see you today as I want to meet one of my friends today who will move to Seattle next month. 　

I am sorry but I can’t see you today. because, I want to spend some time with one of my friend who is moving to Seattle in next month.
Can I make it up for you other time?

お誘いを断ったお友達への埋め合わせも忘れずに(^^) 　

I will be totally rude and cancel up on the plan just because I have to make some time to see a friend of mine who’s going to Seattle next month. Sorry...