One of my female guppies has a split tail?? It just happend last night.... i dont kno wat happend i did have a tetra in their and he was chasing all the females around so i took him out?? now she has a split tail... also a crooked back??

The split tail could be from chasing and nipping or it could be the start of finrot. The crooked back doesn't sound good, this is a symptom of old age or internal illness. You could medicate your tank with an antibacterial medication if you are concerned about possible finrot but there isn't anything to be done about the crooked back, I'm sorry.