It seems you both drifting towards breakup; and end in divorce.
and her Attitute shows(as per your words) she want yo enjoy her life at mothers house and you to pay for her.
make it clear if she stay there you will not pay and pay only half for child.
keep all bill of payments.
File for visitation. if she take away child from you
get back all valuables given to her.
and also inform Police if she took anything and left your house (if she leave next time)
if Possible make audio/video record of her abuse and call our helpline number