My boyfriend and I just split up and we have a 5 month old daughter if I let him have visitation of our daughter can he take her and get temporary custody? State of Ohio

Is he on the birth certificate ?

You need to file for custody ( he can then file for joint if he wants it) fathers normally can get joint custody if there is not a reason he can't. ( if they just ask for it)

You need to work out a visit program with him, since not allowing him to visit the child will also go against you in court when you get there.

If nothing else, have a third party and allow him a evening or afternoon each week with child, till you get visits and custody arranged.

It works best if you both will just agree on custody, child support, and will file a motion together in court.