Does God want me to continue to sacrifice my whole life, even if it means sacrificing it in a way that seems meaningless to me, or does God want me to stop being a coward, and insist upon even minor changes in behavior that will undoubtedly lead to her getting a lawyer (as she has threatened in the past)?
I don’t know how to even begin discerning this.
The Lord wants you to start acting like a Christian husband and father. Read Ephesian 5 tonight, if you want tangible examples. The Church is the Lord’s Bride; Christ is the Church’s groom. Christ was willing to sacrifice himself for His Bride, on the cross. But the Church is still HIs bride, and is subject to Him.
Start being in charge of your family. If your wife does not respect you, then do not tolerate or accept this. (The same is true with your children.) You ultimately are responsible to them, as head of household, so act like it. If aspects of their conduct are unacceptable, then do not accept it. Demand that there be changes. If aspects of your home life are non-Christian, then demand that they change. If, for example, your children are not being raised in the faith, then you need to change this, immediately.
You must do this in a loving and compassionate way - but you still must do it.
========================================================
Look, man, I know the situation is tough. It is especially tough if your spouse is a non-believer; then you cannot use the Biblical/Magisterial teaching to help you, as you try to fix your marriage.
I can empathize with you. Neither you nor I will ever have the perfect, ideal, Brady-Bunch type of family. Sorry to burst your bubble.
But over the past couple of years, I have stopped whining about the situation, and started taking responsibility for it. I started taking a more active role in my marriage. Ultimately, I hope to win back my wife for Christ. And I won’t do that, simply by giving in, or giving up. I don’t know if it will ever happen, but I won’t stop trying.
===================================================
Now, on your specific question on marriage by a justifice of the peace: if you are Catholic, and your marriage was not convalidated by the Bishop, then yes, you could obtain an annulment, based upon defect of form. I think you already know this.
But I strongly advise against this. A better alternative would be to a) get your marriage convalidated today, and b) start carrying out your vocation, with faith and courage.
Could you end up in divorce court? I won’t kid you; it is a real possibility. Many women simply refuse to be part of a real, sacramental marriage. (I could list dozens of reasons, but I will digress.) Hate to say it, but this is a chance you’re going to have to take.