If someone's spouse leaves them and then cheats on them when is the marriage over?
If someone's spouse leaves them and then cheats on them when is the marriage over? Is the cheated on person able to remarry if they are intimate with someone while awaiting the divorce finalization. If the cheated on accepts Christ and is baptized after the events, and repents for the fornication, is the cheated upon still a victim and able to marry or must they remain unmarried?
Clearly I don't know all of the details of the circumstance you have described and I don't know if it is actual or hypothetical. But Jesus' teaching in Matthew 5:32 and Matthew 19:1-9 prohibits divorce except for the instance where one party commits "sexual immorality." As I understand the implications of this teaching, then the "innocent" party is only justified in divorce and remarriage if his/her spouse were guilty of "cheating." If there were no sexual immorality/cheating then the divorce is against God's law (Matthew 19:6) and neither person has the right to remarry, unless of course they reunited with each other (regardless of what they do after the divorce).
As to the circumstances you describe, any "cheating" after the divorce isn't really the cause for the divorce in the first place and I don't see how that would free the other party.
As to the issue of repentance and baptism, repentance addresses a change of will to the pursuit of God's will. If God's will is that husband and wife not divorce except for sexual immorality then that must be the will of the one repenting. If he/she were divorced for reasons other than sexual immorality, then repentance/baptism doesn't really change the circumstances of the divorce, rather forgives the person for their past sins with the expectation that they not return to sin. If the person who has been baptized had divorced his/her spouse for sexual immorality, then they would still be free to remarry according to Matthew 5:32 and Matthew 19:1-9.
I don't know if that addresses all of your questions. Feel free to respond and I'll do my best to point you to the scriptures. Those two passages, along with the parallel ones in Mark 6:17-18, Mark 10:2-12 and Luke 16:18 contain Jesus' comments on the matter. Please read them for yourself and honestly consider the necessary conclusions.