My wife last husband wanted to divorce her on irreconcilable differences. He changed his mind and said to her he wanted to work things out, she refused and wanted to proceed with the divorce because of the abuse and adultery, he also had another child outside their marriage. They proceeded with the divorce under irreconcilable differences even though in her heart she wanted to leave because of the abuse and affairs he were having. She was not in the church of Christ. We met, she then was baptized and now added to the body and I married her. Is our marriage right in God's eyes? And is the law of marriage and divorce that Jesus taught for the church or universal?
God's laws, including those regarding divorce, are universally applied. If they were not, then people would be better off never becoming a Christian because "sin is not imputed when there is no law" (Romans 5:13). But sin is in the world, which is Paul's point at the beginning of Romans. "Therefore, just as through one man sin entered the world, and death through sin, and thus death spread to all men, because all sinned" (Romans 5:12). Thus, the world is accountable to God's laws.
It isn't just Christians who must marry. "Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge" (Hebrews 13:4). Both Paul (I Corinthians 7:12-15) and Peter (I Peter 3:1-2) how to handle marriages to non-believers.
Therefore, most of what you wrote are non-issues. It doesn't matter when she became a Christian.
The point is that the divorce was because her first husband committed adultery, among other problems. It doesn't matter what the court records have down as the reason. In many "no-fault" states, it is recorded as "irreconcilable differences." Obviously the difference in this case was that he thought adultery was fine and she didn't. Nor does it matter these days who filed for divorce first. It is getting very common for the guilty party to file for the divorce so they can continue their sin.
"And I say to you, whoever divorces his wife, except for sexual immorality, and marries another, commits adultery; and whoever marries her who is divorced commits adultery" (Matthew 19:9).
Her marriage ended because her husband was committing adultery. Thus, she is allowed to marry again.