Last name help?

Me and the baby daddy broke things off and i no longer want to hyphenate our last names. Who has final say on babys last name? Hes sayin it has to be hyphenated but i just want mine and said we can hyphenate down the road if things go well with co parenting.

Hes the reason we broke up. Engaged. Cheated on me and has been lying for couple years going on single sites. On other social media pretending to be single