how do i respond to my ex husbands motion to set aside alimony, writ of garnishment, making false statements about me, he has a bench warrant

Your facts are unclear -- the warrant is against him, or you?  In any event, a response is called an "Opposition."  If you do not have a lawyer -- which would be best -- consider using the self-help center forms.  See http://www.familylawselfhelpcenter.org/.  Then consider hiring someone knowledgeable about doing collections to get the money you are owed.