The answer is possibly...
The letter U
I can bow to the enemy: it's bow-shapedU = Yew, commonly used to make bows.
I am the opposite of myself: U = You, the opposite of "myself"
I can help you, if you want to go back: U-Turn.
I am known for staying in a group of my kind: not sureU = Ewe, maybe something to do with the union operator?who usually group together in herds.
The title: the letter U is between T and V in the English alphabet.