used to

意見如下：

“used to”用於表達以前經常會做的事情或行為。

一般而言，“used to”通常用於引出行為或活動，即 “used to (do something)”，上述句子中的 “used to” 用作引出過往的感受雖較為少見，但文法仍是正確的。

如想簡單一點表達例句的意思，可考慮以下表達方法：
1) I felt happy for John who has a good wife.
2) I was happy for John who has a good wife.

題外話，英文文法另有 “be used to”，如 “I am used to playing football in the playground after school.”，意即「習慣做某事情/活動」-「我習慣於放學後在操場上踢足球」。

其他參考資料：
文匯報 – 網上版 – 有關 “used to” 和 “be used to ” 意思的資料
http://paper.wenweipo.com/2008/02/05/ED0802050012.htm

I so happy for John he has a good wife.
I were happy for John has a good wife.

yes. but it also means that you are no longer happy for john who has a good wife