"幸福来的太突然" 英语怎么说?

Happiness suddenly falls on(strikes也可以）me, which is so unimaginable to me that I am afraid it is just in a flash.

in a flash 昙花一现

刚才我把它翻成了一句话 如果你硬要按中文的短句格式翻成3句 也可以这样：Happiness suddenly strikes me.
Even I myself cannot expect it.
But I am afraid it is just in a flash

但是我自己认为翻成一句更好。

The ecastacy daunted on me so suddenly and even I,myself,never forsaw it.While,I am worried that it may be too transient and will not last longer.

幸福来的太突然Suddenly,my happiness comes
连我自己也没想到Even I haven't expected it
但我担心它太短暂But I am afraid that it can not last long

All of a sudden the happiness came without being expected even by myself.
However, I'm worried that is might just be somewhat temporary.

This happiness arrived so quickly. Even I coulld've never expected it. I am afraid, however, that it won't last long.

Happiness comes suddenly
i am not even expecting it
but i am