Do the same thing with the orange line layers. On the Curve layer that you made for the orange lines, we are going to fade the edges out. While holding Option/Alt click on the layer's mask. Grab the Gradient Tool (G). Have the Gradient go from a Black to White fade, set the mode to Multiply on the property bar, and make it a Radial Gradient. Drag from the center of the 'X' to the edge. This will make it fade out.