Sounds like you need to top heavily and then train the remaining branches in a scrog net. You can get the branches to run horizontally instead of continue vertically... for the most part.

There is no way to stop the stretch, not chemically or anything else, but more blue and less red spectrum will control it, but don't do that because the red is there to initiate flowering. Stretch is just a part of the cycle.

It's amazing how much of a top you can cut off and the plant lives. So start looking at your plant and see which of the lower branches peak at your desired height and then visualize how you can spread them out in the scrog net to maximize your canopy. Once you've done that, make sure the plant is happy, healthy and watered / fed and then go to town with your plan.