Why wont my lemon meringue pie stay together?

Firstly, when you cook your lemon filling, be absolutely sure that you BOIL it for at least 30 seconds....cornstarch needs to fully boil in order for it to firm up. Have your meringue ready to top your pie as soon as you put the filling in the crust, the heat of the filling will help to cook the bottom of the meringue....immediately put it in the oven, and refrigerate immediately upon removing from the oven. Leaving it to cool at room temperature will cause the bottom of the meringue to get watery, which is what's causing your pie to separate. I personally do my filling in the microwave because I don't have to stir it constantly to prevent burning while bringing it to a boil. Good luck