Q.I Ruined My Young Meyer Lemon Tree
I was spraying my tree with fertilizer and the leaves have yellow (I guess) burn marks. The leaves are falling off one by painful one. Now that being said, should I cut the branches back? Let it start over? Or will the leaves grow back? I wish I could show you a pic. The leaves are speckled with yellow dots.

It depends on the type lamp. It's been my experience that growing under fluorescent lights is best accomplished using a warm white and a cool white bulb in a two bulb fixture. Distance from lamp to foliage should depend on the plant. The more sun a plant needs, as in citrus, the closer it should be to the bulbs. Warm white and cool white give the same light spectrum as grow bulbs for a fraction of cost. If your plant is tall, you may want to position the fixtures vertically and put the plant between the fixtures so the entire plant gets light instead of just the canopy.

I have my basement with even temp and t5 lamps do you think that is enough for my lemon/ orange tree

Your leaf drop may or may not have been caused by spraying with fertilizer. If you were using the product according to package directions, the fertilizer should not have caused leaf drop. This article might help: https://www.gardeningknowhow.com/edible/fruits/citrus/leaves-falling-off-citrus-tree.htm