Apparently, the last 2 episode have leaked online and many fans have posted spoilers on Tumblr.
In my opinion, that is disrespectful. I would ask you to not watch until the episodes air in the US and Canada but it's up to you.
But what I want you to know if that even when the show has been renewed for a season 4 it doesn't guarantee that we will have a 5th one. But I do know that the ratings for the last episodes can play a very good part in getting more than four seasons.
Nora Zuckerman, one of the writers of the show, has asked those involved to take down the spoilers:
Have a good day ;)