Q.pruned crepe myrtle tree
My tree got much too tall and, therefore, was pruned down to 3 1/2 feet in early April. Fortunately, all 5 trunks, which are about 3 inches in diameter, are sprouting like crazy. However, the new growth is so tender that a recent windy day bent many of them, which are about 6 to 8 inches long. Should I remove some of these fragile shoots in hopes that a few that remain will get strong or what? Thanks for your answer.
This type of pruning is often referred to Crepe Murder.
Harsh pruning leads to unsightly knots in the stems and leaves the tree with weakened branches. The lush growth you mention, is actually structurally weak. This can lead to fungus disease and pests on the tree.
It can take years to reverse this pruning.
Here are some articles and links that will help you get started.
http://www.newgarden.com/notes/crape-murder
https://www.gardeningknowhow.com/ornamental/trees/crepe-myrtle/pruning-crepe-myrtle-trees.htm
https://www.gardeningknowhow.com/ornamental/trees/crepe-myrtle/best-crepe-myrtle-pruning-time-when-to-prune-crepe-myrtle.htm