"Canon 1394 §1 Without prejudice to the provisions of Canon 194, §1, n. 3, a cleric who attempts marriage, even if only civilly, incurs a latae sententiae suspension. If, after warning, he has not reformed and continues to give scandal, he can be progressively punished by deprivations, or even by dismissal from the clerical state.
§2 Without prejudice to the provisions of Canon 694, a religious in perpetual vows who is not a cleric but who attempts marriage, even if only civilly, incurs a latae sententiae interdict.
Canon 1395 §1 Apart from the case mentioned in Canon 1394, a cleric living in concubinage, and a cleric who continues in some other external sin against the sixth commandment of the Decalogue which causes scandal, is to be punished with suspension. To this, other penalties can progressively be added if after a warning he persists in the offence, until eventually he can be dismissed from the clerical state."
saintwiki.com/index.php?title=Code_of_Canon_Law%2C_Book_VI_Part_II:_Penalties_for_Particular_Offenses
For a woman to sin with a priest her sin is also grave and she also is in mortal sin. If she persists in the involvement she remains in that sin so cannot receive Communion, nor can the priest. Unless and until the priest is laicized, they cannot be involved nor can they licitly or validly marry.
leavingthepriesthood.com/The_Laicization_Process_Blog_Archive_through_November_7__2010.pdf