Now comes the "tricky" bit.
Trim back the fusible interfacing close to the stitch line then clip all the way round the fabric heart. I cut a notch at the top and bottom of the heart to make it sit better once it is turned. Make a long slit down the middle of the interfacing so that you can turn everything right sides out. Be very careful NOT to cut into the fabric heart. I usually cut a tiny notch into the interfacing then cut the slit on either side of it. I always go from top to bottom since for me it makes it easier to turn the heart.