我没见过别人这么说过,最好别用,就用It was you who made her sad.
一般疑问句是Was it you made her sad?
在虚拟语气时,it 后面能接were,比如
If it were a sure thing,someone else,far less capable than you,would have already claimed the prize.
如果这是一件理所当然的事情,那么也许比你能力差得多的人早就成功了.