Wife is leaving after giving birth to maybe my child?

Hey guys 24M here, wife is leaving me right after giving birth to a child, who’s birth certificate has father marked as “unknown”. I just found out she’s been cheating on me for at least a year (I think with another military member) I want to get a paternity test and she’s telling me no since she is the only legal guardian, will I win a paternity test if I take this to court? We’ve been married for 3 years.